diff --git a/pkg/noun/allocate.c b/pkg/noun/allocate.c
index 44f7175879..b905ce5912 100644
--- a/pkg/noun/allocate.c
+++ b/pkg/noun/allocate.c
@@ -2131,7 +2131,8 @@ u3a_mark_road(FILE* fil_u)
   tot_w += u3a_maid(fil_u, "  profile batteries", u3a_mark_noun(u3R->pro.don));
   tot_w += u3a_maid(fil_u, "  profile doss", u3a_mark_noun(u3R->pro.day));
   tot_w += u3a_maid(fil_u, "  new profile trace", u3a_mark_noun(u3R->pro.trace));
-  tot_w += u3a_maid(fil_u, "  memoization cache", u3h_mark(u3R->cax.har_p));
+  tot_w += u3a_maid(fil_u, "  transient memoization cache", u3h_mark(u3R->cax.har_p));
+  tot_w += u3a_maid(fil_u, "  persistent memoization cache", u3h_mark(u3R->cax.per_p));
   return   u3a_maid(fil_u, "total road stuff", tot_w);
 }
 
@@ -2158,6 +2159,7 @@ u3a_rewrite_compact(void)
   u3a_rewrite_noun(u3R->pro.day);
   u3a_rewrite_noun(u3R->pro.trace);
   u3h_rewrite(u3R->cax.har_p);
+  u3h_rewrite(u3R->cax.per_p);
 
   u3R->ski.gul = u3a_rewritten_noun(u3R->ski.gul);
   u3R->bug.tax = u3a_rewritten_noun(u3R->bug.tax);
@@ -2166,6 +2168,7 @@ u3a_rewrite_compact(void)
   u3R->pro.day = u3a_rewritten_noun(u3R->pro.day);
   u3R->pro.trace = u3a_rewritten_noun(u3R->pro.trace);
   u3R->cax.har_p = u3a_rewritten(u3R->cax.har_p);
+  u3R->cax.per_p = u3a_rewritten(u3R->cax.per_p);
 }
 
 /* _ca_print_box(): heuristically print the contents of an allocation box.
diff --git a/pkg/noun/allocate.h b/pkg/noun/allocate.h
index be50793002..a31488642c 100644
--- a/pkg/noun/allocate.h
+++ b/pkg/noun/allocate.h
@@ -154,11 +154,11 @@
 
         u3a_jets jed;                         //  jet dashboard
 
-        struct {                              // bytecode state
-          u3p(u3h_root) har_p;                // formula->post of bytecode
+        struct {                              //  bytecode state
+          u3p(u3h_root) har_p;                //  formula->post of bytecode
         } byc;
 
-        struct {                              //  namespace
+        struct {                              //  scry namespace
           u3_noun gul;                        //  (list $+(* (unit (unit)))) now
         } ski;
 
@@ -175,8 +175,11 @@
           u3_noun day;                        //  doss, only in u3H (moveme)
         } pro;
 
-        struct {                              //  memoization
-          u3p(u3h_root) har_p;                //  (map (pair term noun) noun)
+        struct {                              //  memoization caches
+          u3p(u3h_root) har_p;                //  transient
+          u3p(u3h_root) per_p;                //  persistent
+          u3p(u3h_root) fod_p;                //  ford  NB: not used
+          u3p(u3h_root) sam_p;                //  ames  NB: not used
         } cax;
       } u3a_road;
       typedef u3a_road u3_road;
@@ -232,7 +235,7 @@
     /* u3a_is_atom(): yes if noun [som] is direct atom or indirect atom.
     */
 #     define u3a_is_atom(som)    c3o(u3a_is_cat(som), \
-                                         u3a_is_pug(som))
+                                     u3a_is_pug(som))
 #     define u3ud(som)           u3a_is_atom(som)
 
     /* u3a_is_cell: yes if noun [som] is cell.
diff --git a/pkg/noun/hashtable.h b/pkg/noun/hashtable.h
index a117f50011..291ef28a0c 100644
--- a/pkg/noun/hashtable.h
+++ b/pkg/noun/hashtable.h
@@ -16,9 +16,8 @@
     ***  corresponding to the 32-slot nodes for everything under
     ***  the root node.
     ***
-    ***  We store an extra "freshly warm" bit for a simple
-    ***  clock-algorithm reclamation policy, not yet implemented.
-    ***  Search "clock algorithm" to figure it out.
+    ***  We store an extra "freshly warm" bit and use it for a simple
+    ***  clock-algorithm reclamation policy.
     **/
       /* u3h_slot: map slot.
       **
diff --git a/pkg/noun/jets.c b/pkg/noun/jets.c
index dcabcdb559..13e417dab6 100644
--- a/pkg/noun/jets.c
+++ b/pkg/noun/jets.c
@@ -18,15 +18,6 @@
 #include "vortex.h"
 #include "xtract.h"
 
-/**  Data structures.
-**/
-
-/* _cj_hank: cached hook information.
- */
-typedef struct {
-  u3_weak  hax;                     //  axis of hooked inner core
-  u3j_site sit_u;                   //  call-site data
-} _cj_hank;
 
 /**  Functions.
 **/
@@ -1069,7 +1060,7 @@ _cj_prog(u3_weak loc, u3_noun fol)
 /* cj_hank_find(): find cached hook information, keyed by arbitrary
  *                 prefix and term cords. RETAIN.
  */
-static _cj_hank*
+static u3j_hank*
 _cj_hank_find(u3_noun pre, u3_noun tam)
 {
   u3_noun key = u3nc(u3k(pre), u3k(tam));
@@ -1077,10 +1068,10 @@ _cj_hank_find(u3_noun pre, u3_noun tam)
 
   if ( u3_none != got ) {
     u3z(key);
-    return u3to(_cj_hank, got);
+    return u3to(u3j_hank, got);
   }
   else {
-    _cj_hank* new_u = u3a_walloc(c3_wiseof(_cj_hank));
+    u3j_hank* new_u = u3a_walloc(c3_wiseof(u3j_hank));
     u3a_road* rod_u = u3R;
 
     while ( rod_u->par_p && u3_none == got ) {
@@ -1092,7 +1083,7 @@ _cj_hank_find(u3_noun pre, u3_noun tam)
       new_u->hax = u3_none;
     }
     else {
-      _cj_hank* old_u = u3to(_cj_hank, got);
+      u3j_hank* old_u = u3to(u3j_hank, got);
       if ( u3_none != (new_u->hax = old_u->hax) ) {
         //  it's unusual but safe to "take" here, because
         //  u3a_take will no-op on senior nouns (just as u3k would)
@@ -1101,7 +1092,7 @@ _cj_hank_find(u3_noun pre, u3_noun tam)
       }
     }
 
-    u3h_put(u3R->jed.han_p, key, u3of(_cj_hank, new_u));
+    u3h_put(u3R->jed.han_p, key, u3of(u3j_hank, new_u));
     u3z(key);
     return new_u;
   }
@@ -1112,7 +1103,7 @@ _cj_hank_find(u3_noun pre, u3_noun tam)
  *                  core on return if valid. RETAIN.
  */
 static c3_o
-_cj_hank_fine(_cj_hank* han_u, u3_noun cor, u3_noun *inn)
+_cj_hank_fine(u3j_hank* han_u, u3_noun cor, u3_noun *inn)
 {
   u3_noun hax = han_u->hax;
   if ( u3_none == hax ) {
@@ -1134,7 +1125,7 @@ _cj_hank_fine(_cj_hank* han_u, u3_noun cor, u3_noun *inn)
 /* _cj_hank_lose(): release memory maintained in a hook cache.
 */
 static void
-_cj_hank_lose(_cj_hank* han_u)
+_cj_hank_lose(u3j_hank* han_u)
 {
   if ( u3_none != han_u->hax ) {
     u3z(han_u->hax);
@@ -1145,7 +1136,7 @@ _cj_hank_lose(_cj_hank* han_u)
 /* _cj_hank_fill(): slow path, populate han_u.
  */
 static u3_noun
-_cj_hank_fill(_cj_hank* han_u, u3_noun tam, u3_noun cor)
+_cj_hank_fill(u3j_hank* han_u, u3_noun tam, u3_noun cor)
 {
   u3_weak   loc, col;
   u3_noun   got, pat, nam, huc;
@@ -1642,7 +1633,7 @@ u3j_cook(const c3_c* key_c,
          const c3_c* tam_c)
 {
   u3_noun pro, key, tam, inn;
-  _cj_hank* han_u;
+  u3j_hank* han_u;
 
   u3t_on(glu_o);
   key = u3i_string(key_c);
@@ -1992,11 +1983,11 @@ u3j_rite_mine(u3j_rite* rit_u, u3_noun clu, u3_noun cor)
 
 /* _cj_take_hank_cb(): u3h_take_with cb for taking hanks
 */
-static u3p(_cj_hank)
-_cj_take_hank_cb(u3p(_cj_hank) nah_p)
+static u3p(u3j_hank)
+_cj_take_hank_cb(u3p(u3j_hank) nah_p)
 {
-  _cj_hank* nah_u = u3to(_cj_hank, nah_p);
-  _cj_hank* han_u = u3a_walloc(c3_wiseof(_cj_hank));
+  u3j_hank* nah_u = u3to(u3j_hank, nah_p);
+  u3j_hank* han_u = u3a_walloc(c3_wiseof(u3j_hank));
 
   if ( u3_none == nah_u->hax ) {
     han_u->hax = u3_none;
@@ -2007,7 +1998,7 @@ _cj_take_hank_cb(u3p(_cj_hank) nah_p)
     u3j_site_take(&(han_u->sit_u), &(nah_u->sit_u));
   }
 
-  return u3of(_cj_hank, han_u);
+  return u3of(u3j_hank, han_u);
 }
 
 /* u3j_take(): copy junior jet state.
@@ -2029,25 +2020,25 @@ static void
 _cj_merge_hank_cb(u3_noun kev, void* wit)
 {
   u3p(u3h_root) han_p = *(u3p(u3h_root)*)wit;
-  _cj_hank* nah_u;
+  u3j_hank* nah_u;
   u3_noun key;
-  u3p(_cj_hank) nah_p;
+  u3p(u3j_hank) nah_p;
   u3x_cell(kev, &key, &nah_p);
 
-  nah_u = u3to(_cj_hank, nah_p);
+  nah_u = u3to(u3j_hank, nah_p);
 
   if ( u3_none == nah_u->hax ) {
     u3a_wfree(nah_u);
   }
   else {
-    _cj_hank* han_u;
+    u3j_hank* han_u;
     u3_weak     got = u3h_git(u3R->jed.han_p, key);
 
     if ( u3_none == got )  {
       han_u = nah_u;
     }
     else {
-      han_u = u3to(_cj_hank, got);
+      han_u = u3to(u3j_hank, got);
 
       if ( u3_none != han_u->hax ) {
         u3z(han_u->hax);
@@ -2058,7 +2049,7 @@ _cj_merge_hank_cb(u3_noun kev, void* wit)
       u3a_wfree(nah_u);
     }
 
-    u3h_put(han_p, key, u3of(_cj_hank, han_u));
+    u3h_put(han_p, key, u3of(u3j_hank, han_u));
   }
 }
 
@@ -2170,7 +2161,7 @@ _cj_warm_tap(u3_noun kev, void* wit)
 static void
 _cj_ream_hank(u3_noun kev)
 {
-  u3j_site_ream(&(u3to(_cj_hank, u3t(kev))->sit_u));
+  u3j_site_ream(&(u3to(u3j_hank, u3t(kev))->sit_u));
 }
 
 /* u3j_ream(): rebuild warm state
@@ -2304,7 +2295,7 @@ static void
 _cj_mark_hank(u3_noun kev, void* dat)
 {
   c3_w* tot_w = (c3_w*) dat;
-  _cj_hank* han_u = u3to(_cj_hank, u3t(kev));
+  u3j_hank* han_u = u3to(u3j_hank, u3t(kev));
   *tot_w += u3a_mark_ptr(han_u);
   if ( u3_none != han_u->hax ) {
     *tot_w += u3a_mark_noun(han_u->hax);
@@ -2337,12 +2328,12 @@ u3j_mark(FILE* fil_u)
   return u3a_maid(fil_u, "total jet stuff", tot_w);
 }
 
-/* _cj_free_hank(): free an entry from the hank cache.
+/* u3j_free_hank(): free an entry from the hank cache.
 */
-static void
-_cj_free_hank(u3_noun kev)
+void
+u3j_free_hank(u3_noun kev)
 {
-  _cj_hank* han_u = u3to(_cj_hank, u3t(kev));
+  u3j_hank* han_u = u3to(u3j_hank, u3t(kev));
   if ( u3_none != han_u->hax ) {
     u3z(han_u->hax);
     u3j_site_lose(&(han_u->sit_u));
@@ -2355,7 +2346,7 @@ _cj_free_hank(u3_noun kev)
 void
 u3j_free(void)
 {
-  u3h_walk(u3R->jed.han_p, _cj_free_hank);
+  u3h_walk(u3R->jed.han_p, u3j_free_hank);
   u3h_free(u3R->jed.war_p);
   u3h_free(u3R->jed.cod_p);
   u3h_free(u3R->jed.han_p);
@@ -2379,7 +2370,7 @@ u3j_reclaim(void)
   // }
   //  clear the jet hank cache
   //
-  u3h_walk(u3R->jed.han_p, _cj_free_hank);
+  u3h_walk(u3R->jed.han_p, u3j_free_hank);
   u3h_free(u3R->jed.han_p);
   u3R->jed.han_p = u3h_new();
 }
diff --git a/pkg/noun/jets.h b/pkg/noun/jets.h
index 9c5241c5db..1440f7558a 100644
--- a/pkg/noun/jets.h
+++ b/pkg/noun/jets.h
@@ -126,6 +126,13 @@
         u3p(u3j_fink) fin_p;          //  fine check
       } u3j_site;
 
+      /* u3j_hank: cached hook information.
+       */
+      typedef struct {
+        u3_weak  hax;                     //  axis of hooked inner core
+        u3j_site sit_u;                   //  call-site data
+      } u3j_hank;
+
   /** Globals.
   **/
     /* u3_Dash: jet dashboard.
@@ -297,6 +304,11 @@
         void
         u3j_free(void);
 
+      /* u3j_free_hank(): free an entry from the hank cache.
+      */
+        void
+        u3j_free_hank(u3_noun kev);
+
       /* u3j_reclaim(): clear ad-hoc persistent caches to reclaim memory.
       */
         void
diff --git a/pkg/noun/jets/f/ut_crop.c b/pkg/noun/jets/f/ut_crop.c
index 1969a13a3d..189564d0c3 100644
--- a/pkg/noun/jets/f/ut_crop.c
+++ b/pkg/noun/jets/f/ut_crop.c
@@ -20,7 +20,7 @@ u3wfu_crop(u3_noun cor)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__crop + ((!!vet) << 8);
     u3_noun key = u3z_key_3(fun_m, sut, ref, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -28,7 +28,7 @@ u3wfu_crop(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/jets/f/ut_fish.c b/pkg/noun/jets/f/ut_fish.c
index e7505b9345..e8acbd43cf 100644
--- a/pkg/noun/jets/f/ut_fish.c
+++ b/pkg/noun/jets/f/ut_fish.c
@@ -21,7 +21,7 @@ u3wfu_fish(u3_noun cor)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__fish + ((!!vet) << 8);
     u3_noun key = u3z_key_3(fun_m, sut, axe, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -29,7 +29,7 @@ u3wfu_fish(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/jets/f/ut_fuse.c b/pkg/noun/jets/f/ut_fuse.c
index f9fac33a4d..8e4e1a6135 100644
--- a/pkg/noun/jets/f/ut_fuse.c
+++ b/pkg/noun/jets/f/ut_fuse.c
@@ -20,7 +20,7 @@ u3wfu_fuse(u3_noun cor)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__fuse + ((!!vet) << 8);
     u3_noun key = u3z_key_3(fun_m, sut, ref, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -28,7 +28,7 @@ u3wfu_fuse(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/jets/f/ut_mint.c b/pkg/noun/jets/f/ut_mint.c
index fc8424854a..618e7291fd 100644
--- a/pkg/noun/jets/f/ut_mint.c
+++ b/pkg/noun/jets/f/ut_mint.c
@@ -22,7 +22,7 @@ u3wfu_mint(u3_noun cor)
     c3_m  fun_m = 141 + c3__mint;
     u3_noun vet = u3r_at(u3qfu_van_vet, van);
     u3_noun key = u3z_key_5(fun_m, vet, sut, gol, gen, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -30,7 +30,7 @@ u3wfu_mint(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/jets/f/ut_mull.c b/pkg/noun/jets/f/ut_mull.c
index 98e62ca57e..767ab3c51a 100644
--- a/pkg/noun/jets/f/ut_mull.c
+++ b/pkg/noun/jets/f/ut_mull.c
@@ -23,7 +23,7 @@ u3wfu_mull(u3_noun cor)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__mull + ((!!vet) << 8);
     u3_noun key = u3z_key_5(fun_m, sut, gol, dox, gen, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -31,7 +31,7 @@ u3wfu_mull(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/jets/f/ut_nest.c b/pkg/noun/jets/f/ut_nest.c
index 765081a5cb..9bc53bf0f9 100644
--- a/pkg/noun/jets/f/ut_nest.c
+++ b/pkg/noun/jets/f/ut_nest.c
@@ -27,7 +27,7 @@ u3wfu_nest_dext(u3_noun dext_core)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__dext + ((!!vet) << 8);
     u3_noun key = u3z_key_3(fun_m, sut, ref, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -39,7 +39,7 @@ u3wfu_nest_dext(u3_noun dext_core)
       if ( ((c3y == pro) && (u3_nul == reg)) ||
            ((c3n == pro) && (u3_nul == seg)) )
       {
-        return u3z_save(key, pro);
+        return u3z_save(u3z_memo_toss, key, pro);
       }
       else {
         u3z(key);
diff --git a/pkg/noun/jets/f/ut_rest.c b/pkg/noun/jets/f/ut_rest.c
index 3fdbed23b0..87ff60fa68 100644
--- a/pkg/noun/jets/f/ut_rest.c
+++ b/pkg/noun/jets/f/ut_rest.c
@@ -20,7 +20,7 @@ u3wfu_rest(u3_noun cor)
     u3_weak vet = u3r_at(u3qfu_van_vet, van);
     c3_m  fun_m = 141 + c3__rest + ((!!vet) << 8);
     u3_noun key = u3z_key_3(fun_m, sut, leg, bat);
-    u3_weak pro = u3z_find(key);
+    u3_weak pro = u3z_find(u3z_memo_toss, key);
 
     if ( u3_none != pro ) {
       u3z(key);
@@ -28,7 +28,7 @@ u3wfu_rest(u3_noun cor)
     }
     else {
       pro = u3n_nock_on(u3k(cor), u3k(u3x_at(u3x_bat, cor)));
-      return u3z_save(key, pro);
+      return u3z_save(u3z_memo_toss, key, pro);
     }
   }
 }
diff --git a/pkg/noun/manage.c b/pkg/noun/manage.c
index 60787bde34..ec1f32524b 100644
--- a/pkg/noun/manage.c
+++ b/pkg/noun/manage.c
@@ -1,6 +1,8 @@
 /// @file
 
-#include "manage.h"
+#include "pkg/noun/manage.h"
+#include "pkg/noun/v2/manage.h"
+#include "pkg/noun/v3/manage.h"
 
 #include <ctype.h>
 #include <errno.h>
@@ -473,9 +475,8 @@ u3m_mark(FILE* fil_u)
 static void
 _pave_parts(void)
 {
-  // TODO: pass `u3_Host.ops_u.hap_w` into `noun` library as an argument and use
-  // as size of memo cache.
-  u3R->cax.har_p = u3h_new_cache(50000);
+  u3R->cax.har_p = u3h_new_cache(u3C.hap_w);  //  transient
+  u3R->cax.per_p = u3h_new_cache(u3C.per_w);  //  persistent
   u3R->jed.war_p = u3h_new();
   u3R->jed.cod_p = u3h_new();
   u3R->jed.han_p = u3h_new();
@@ -597,7 +598,8 @@ _find_home(void)
 
   switch ( ver_w ) {
     case 1: u3m_v2_migrate();
-    case 2: break;
+    case 2: u3m_v3_migrate();
+    case 3: break;
     default: {
       fprintf(stderr, "loom: checkpoint version mismatch: "
                       "have %u, need %u\r\n",
@@ -991,6 +993,7 @@ u3m_love(u3_noun pro)
   //
   u3p(u3h_root) byc_p = u3R->byc.har_p;
   u3a_jets      jed_u = u3R->jed;
+  u3p(u3h_root) per_p = u3R->cax.per_p;
 
   //  fallback to parent road (child heap on parent's stack)
   //
@@ -1001,6 +1004,7 @@ u3m_love(u3_noun pro)
   pro   = u3a_take(pro);
   jed_u = u3j_take(jed_u);
   byc_p = u3n_take(byc_p);
+  per_p = u3h_take(per_p);
 
   //  pop the stack
   //
@@ -1011,6 +1015,7 @@ u3m_love(u3_noun pro)
   //
   u3j_reap(jed_u);
   u3n_reap(byc_p);
+  u3z_reap(u3z_memo_keep, per_p);
 
   return pro;
 }
diff --git a/pkg/noun/nock.c b/pkg/noun/nock.c
index 6ac08779ef..452b04c309 100644
--- a/pkg/noun/nock.c
+++ b/pkg/noun/nock.c
@@ -619,7 +619,7 @@ _n_melt(u3_noun ops, c3_w* byc_w, c3_w* cal_w,
 
         case SKIB: case SLIB: {
           c3_l tot_l = 0,
-               sip_l = u3h(u3t(op));
+               sip_l = u3h(u3t(u3t(op)));
           c3_w j_w, k_w = i_w;
           for ( j_w = 0; j_w < sip_l; ++j_w ) {
             tot_l += siz_y[++k_w];
@@ -830,7 +830,9 @@ _n_prog_asm(u3_noun ops, u3n_prog* pog_u, u3_noun sip)
           _n_prog_asm_inx(buf_y, &i_w, mem_s, cod);
           mem_u        = &(pog_u->mem_u.sot_u[mem_s++]);
           mem_u->sip_l = sip_l;
-          mem_u->key   = u3k(u3t(u3t(op)));
+          // [op_y, cid, mem_w, nef]
+          mem_u->key   = u3k(u3t(u3t(u3t(op))));
+          mem_u->cid   = u3h(u3t(op));
           break;
         }
 
@@ -1117,16 +1119,21 @@ _n_bint(u3_noun* ops, u3_noun hif, u3_noun nef, c3_o los_o, c3_o tel_o)
         c3_w mem_w = 0;
         c3_y op_y;
 
-        // we just throw away the hint (why is this not a static hint?)
         tot_w += _n_comp(ops, hod, c3n, c3n);
         ++tot_w; _n_emit(ops, TOSS);
 
-        // memoizing code always loses TOS because SAVE needs [pro key]
         mem_w += _n_comp(&mem, nef, c3y, c3n);
         ++mem_w; _n_emit(&mem, SAVE);
 
         op_y   = (c3y == los_o) ? SLIB : SKIB; // overflows to SLIS / SKIS
-        ++tot_w; _n_emit(ops, u3nt(op_y, mem_w, u3k(nef)));
+        u3z_cid cid = u3z_memo_toss;
+        {
+          u3_weak con = u3r_skip(hod);
+          if ( (u3_none != con) && (c3y == u3du(con)) ) {
+            cid = u3z_memo_keep;
+          }
+        }
+        ++tot_w; _n_emit(ops, u3nq(op_y, cid, mem_w, u3k(nef)));
         tot_w += mem_w; _n_apen(ops, mem);
         break;
       }
@@ -2610,9 +2617,9 @@ _n_burn(u3n_prog* pog_u, u3_noun bus, c3_ys mov, c3_ys off)
     skim_out:
       o     = u3k(mem_u->key);
       x     = u3nc(x, o);
-      o     = u3z_find_m(144 + c3__nock, x);
+      o     = u3z_find_m(mem_u->cid, 144 + c3__nock, x);
       if ( u3_none == o ) {
-        _n_push(mov, off, x);
+        _n_push(mov, off, u3nc(mem_u->cid, x));
         _n_push(mov, off, u3k(u3h(x)));
       }
       else {
@@ -2623,11 +2630,16 @@ _n_burn(u3n_prog* pog_u, u3_noun bus, c3_ys mov, c3_ys off)
       BURN();
 
     do_save:
-      x   = _n_pep(mov, off);
+      x   = _n_pep(mov, off);  // product
       top = _n_peek(off);
       o   = *top;
-      if ( &(u3H->rod_u) != u3R ) {
-        u3z_save_m(144 + c3__nock, o, x);
+      if ( ( u3z_memo_toss == u3h(o) )
+         ? ( &(u3H->rod_u) != u3R )
+         : ( 0 == u3R->ski.gul ) ) {  //  prevents userspace from persistence
+        u3z_save_m(u3h(o), 144 + c3__nock, u3t(o), x);
+      }
+      else if ( u3z_memo_keep == u3h(o) ) {
+        fprintf(stderr, "\r\nnock: userspace can't save to persistent cache\r\n");
       }
       *top = x;
       u3z(o);
@@ -2853,6 +2865,7 @@ _cn_take_prog_dat(u3n_prog* dst_u, u3n_prog* src_u)
     u3n_memo* ome_u = &(dst_u->mem_u.sot_u[i_w]);
     ome_u->sip_l    = emo_u->sip_l;
     ome_u->key      = u3a_take(emo_u->key);
+    ome_u->cid      = emo_u->cid;
   }
 
   for ( i_w = 0; i_w < src_u->cal_u.len_w; ++i_w ) {
@@ -2918,6 +2931,7 @@ _cn_merge_prog_dat(u3n_prog* dst_u, u3n_prog* src_u)
     u3z(emo_u->key);
     emo_u->sip_l    = ome_u->sip_l;
     emo_u->key      = ome_u->key;
+    emo_u->cid      = ome_u->cid;
   }
 
   for ( i_w = 0; i_w < src_u->cal_u.len_w; ++i_w ) {
diff --git a/pkg/noun/nock.h b/pkg/noun/nock.h
index 7dded22058..7baf7351d8 100644
--- a/pkg/noun/nock.h
+++ b/pkg/noun/nock.h
@@ -8,6 +8,7 @@
 #include "c3.h"
 #include "jets.h"
 #include "types.h"
+#include "zave.h"
 
   /** Data structures.
   ***
@@ -18,6 +19,7 @@
   typedef struct {
     c3_l    sip_l;
     u3_noun key;
+    u3z_cid cid;
   } u3n_memo;
 
   /* u3n_prog: program compiled from nock
diff --git a/pkg/noun/options.h b/pkg/noun/options.h
index 52732d2655..29ca6ce9d9 100644
--- a/pkg/noun/options.h
+++ b/pkg/noun/options.h
@@ -17,6 +17,8 @@
         c3_w    wag_w;                        //  flags (both ways)
         size_t  wor_i;                        //  loom word-length (<= u3a_words)
         c3_w    tos_w;                        //  loom toss skip-length
+        c3_w    hap_w;                        //  transient memoization cache size
+        c3_w    per_w;                        //  persistent memoization cache size
         void (*stderr_log_f)(c3_c*);          //  errors from c code
         void (*slog_f)(u3_noun);              //  function pointer for slog
         void (*sign_hold_f)(void);            //  suspend system signal regime
diff --git a/pkg/noun/retrieve.c b/pkg/noun/retrieve.c
index d1790c7320..cc1add4c9c 100644
--- a/pkg/noun/retrieve.c
+++ b/pkg/noun/retrieve.c
@@ -1903,3 +1903,28 @@ u3r_mug(u3_noun veb)
 
   return mug_l;
 }
+
+/* u3r_skip():
+**
+**  Extract a constant from a formula, ignoring
+**  safe/static hints, doing no computation.
+*/
+u3_weak
+u3r_skip(u3_noun fol) {
+  while ( c3y == u3du(fol) ) {
+    switch ( u3h(fol) ) {
+      default: return u3_none;
+      case 1:  return u3t(fol);
+      case 11: {
+        u3_noun arg = u3t(fol),
+                hod = u3h(arg);
+
+        if ( (c3y == u3du(hod)) && (u3_none == u3r_skip(u3t(hod))) ) {
+          return u3_none;
+        }
+        fol = u3t(arg);
+      }
+    }
+  }
+  return u3_none;
+}
diff --git a/pkg/noun/retrieve.h b/pkg/noun/retrieve.h
index a98a5e4697..f382ff6db0 100644
--- a/pkg/noun/retrieve.h
+++ b/pkg/noun/retrieve.h
@@ -486,4 +486,11 @@
         c3_y*
         u3r_tape(u3_noun a);
 
+      /* u3r_skip():
+      **
+      **  Extract a constant from a formula, ignoring
+      **  safe/static hints, doing no computation.
+      */
+        u3_weak u3r_skip(u3_noun fol);
+
 #endif /* ifndef U3_RETRIEVE_H */
diff --git a/pkg/noun/v1/allocate.c b/pkg/noun/v1/allocate.c
index 226aa33f00..29a1f5de77 100644
--- a/pkg/noun/v1/allocate.c
+++ b/pkg/noun/v1/allocate.c
@@ -210,10 +210,10 @@ u3a_v1_reclaim(void)
   u3h_v1_free_nodes(u3R_v1->cax.har_p);
 }
 
-/* _me_lose_north(): lose on a north road.
+/* _me_v1_lose_north(): lose on a north road.
 */
 static void
-_me_lose_north(u3_noun dog)
+_me_v1_lose_north(u3_noun dog)
 {
 top:
   {
@@ -234,7 +234,7 @@ _me_lose_north(u3_noun dog)
           u3_noun     t_dog = dog_u->tel;
 
           if ( !_(u3a_v1_is_cat(h_dog)) ) {
-            _me_lose_north(h_dog);
+            _me_v1_lose_north(h_dog);
           }
           u3a_v1_wfree(dog_w);
           if ( !_(u3a_v1_is_cat(t_dog)) ) {
@@ -256,6 +256,6 @@ void
 u3a_v1_lose(u3_noun som)
 {
   if ( !_(u3a_v1_is_cat(som)) ) {
-    _me_lose_north(som);
+    _me_v1_lose_north(som);
   }
 }
diff --git a/pkg/noun/v1/jets.c b/pkg/noun/v1/jets.c
index be13a63d49..272930e11d 100644
--- a/pkg/noun/v1/jets.c
+++ b/pkg/noun/v1/jets.c
@@ -9,19 +9,6 @@
 #include "pkg/noun/v1/allocate.h"
 #include "pkg/noun/v1/hashtable.h"
 
-/**  Data structures.
-**/
-
-/* _cj_v1_hank: cached hook information.
-**       NB: copy of _cj_hank from pkg/noun/jets.c
- */
-typedef struct {
-  u3_weak  hax;                     //  axis of hooked inner core
-  u3j_v1_site sit_u;                   //  call-site data
-} _cj_v1_hank;
-
-/**  Functions.
-**/
 
 /* _cj_fink_free(): lose and free everything in a u3j_v1_fink.
 */
@@ -75,13 +62,12 @@ u3j_v1_site_lose(u3j_v1_site* sit_u)
 }
 
 /* _cj_v1_free_hank(): free an entry from the hank cache.
-**              NB: copy of _cj_v1_free_hank() from pkg/noun/jets.c
 */
 static void
 _cj_v1_free_hank(u3_noun kev)
 {
   u3a_v1_cell* cel_u = (u3a_v1_cell*) u3a_v1_to_ptr(kev);
-  _cj_v1_hank* han_u = u3to(_cj_v1_hank, cel_u->tel);
+  u3j_v1_hank* han_u = u3to(u3j_v1_hank, cel_u->tel);
   if ( u3_none != han_u->hax ) {
     u3a_v1_lose(han_u->hax);
     u3j_v1_site_lose(&(han_u->sit_u));
diff --git a/pkg/noun/v1/jets.h b/pkg/noun/v1/jets.h
index 1711a0e675..bf3dfe6afe 100644
--- a/pkg/noun/v1/jets.h
+++ b/pkg/noun/v1/jets.h
@@ -10,6 +10,7 @@
   **/
 #     define u3j_v1_fink       u3j_v2_fink
 #     define u3j_v1_fist       u3j_v2_fist
+#     define u3j_v1_hank       u3j_v2_hank
 #     define u3j_v1_rite       u3j_v2_rite
 #     define u3j_v1_site       u3j_v2_site
 
@@ -23,11 +24,11 @@
     /* u3j_v1_rite_lose(): lose references of u3j_rite (but do not free).
     */
       void
-      u3j_v1_rite_lose(u3j_rite* rit_u);
+      u3j_v1_rite_lose(u3j_v1_rite* rit_u);
 
     /* u3j_v1_site_lose(): lose references of u3j_site (but do not free).
     */
       void
-      u3j_v1_site_lose(u3j_site* sit_u);
+      u3j_v1_site_lose(u3j_v1_site* sit_u);
 
 #endif /* ifndef U3_JETS_V1_H */
diff --git a/pkg/noun/v1/nock.c b/pkg/noun/v1/nock.c
index 4e0de27dc2..cce00b28b6 100644
--- a/pkg/noun/v1/nock.c
+++ b/pkg/noun/v1/nock.c
@@ -22,17 +22,10 @@ u3n_v1_reclaim(void)
 }
 
 /* _cn_v1_prog_free(): free memory retained by program pog_u
-**              NB: copy of _cn_v1_prog_free in pkg/noun/nock.c
 */
 static void
 _cn_v1_prog_free(u3n_v1_prog* pog_u)
 {
-  // fix up pointers for loom portability
-  // pog_u->byc_u.ops_y = (c3_y*) ((void*) pog_u) + sizeof(u3n_v1_prog);
-  // pog_u->lit_u.non   = (u3_noun*) (pog_u->byc_u.ops_y + pog_u->byc_u.len_w);
-  // pog_u->mem_u.sot_u = (u3n_memo*) (pog_u->lit_u.non + pog_u->lit_u.len_w);
-  // pog_u->cal_u.sit_u = (u3j_site*) (pog_u->mem_u.sot_u + pog_u->mem_u.len_w);
-  // pog_u->reg_u.rit_u = (u3j_rite*) (pog_u->cal_u.sit_u + pog_u->cal_u.len_w);
 
   c3_w dex_w;
   for (dex_w = 0; dex_w < pog_u->lit_u.len_w; ++dex_w) {
@@ -47,13 +40,21 @@ _cn_v1_prog_free(u3n_v1_prog* pog_u)
   for (dex_w = 0; dex_w < pog_u->reg_u.len_w; ++dex_w) {
     u3j_v1_rite_lose(&(pog_u->reg_u.rit_u[dex_w]));
   }
+
+  // fix up pointers for loom portability
+  pog_u->byc_u.ops_y = (c3_y*) ((void*) pog_u) + sizeof(u3n_v1_prog);
+  pog_u->lit_u.non   = (u3_noun*) (pog_u->byc_u.ops_y + pog_u->byc_u.len_w);
+  pog_u->mem_u.sot_u = (u3n_v1_memo*) (pog_u->lit_u.non + pog_u->lit_u.len_w);
+  pog_u->cal_u.sit_u = (u3j_v1_site*) (pog_u->mem_u.sot_u + pog_u->mem_u.len_w);
+  pog_u->reg_u.rit_u = (u3j_rite*) (pog_u->cal_u.sit_u + pog_u->cal_u.len_w);
+
   u3a_v1_free(pog_u);
 }
 
-/* _n_feb(): u3h_v1_walk helper for u3n_v1_free
+/* _n_v1_feb(): u3h_v1_walk helper for u3n_v1_free
  */
 static void
-_n_feb(u3_noun kev)
+_n_v1_feb(u3_noun kev)
 {
   u3a_v1_cell *cel_u = (u3a_v1_cell*) u3a_v1_to_ptr(kev);
   _cn_v1_prog_free(u3to(u3n_v1_prog, cel_u->tel));
@@ -65,6 +66,6 @@ void
 u3n_v1_free()
 {
   u3p(u3h_v1_root) har_p = u3R_v1->byc.har_p;
-  u3h_v1_walk(har_p, _n_feb);
+  u3h_v1_walk(har_p, _n_v1_feb);
   u3h_v1_free_nodes(har_p);
 }
diff --git a/pkg/noun/v1/nock.h b/pkg/noun/v1/nock.h
index 08a7a5959a..5320307b6b 100644
--- a/pkg/noun/v1/nock.h
+++ b/pkg/noun/v1/nock.h
@@ -7,6 +7,7 @@
 
   /**  Aliases.
   **/
+#     define  u3n_v1_memo  u3n_v2_memo
 #     define  u3n_v1_prog  u3n_v2_prog
 
   /**  Functions.
diff --git a/pkg/noun/v2/allocate.h b/pkg/noun/v2/allocate.h
index 82b1826adb..b08ffd9c69 100644
--- a/pkg/noun/v2/allocate.h
+++ b/pkg/noun/v2/allocate.h
@@ -21,6 +21,7 @@
 #     define u3a_v2_is_north     u3a_is_north
 #     define u3a_v2_is_pom       u3a_is_pom
 #     define u3a_v2_is_pug       u3a_is_pug
+#     define u3a_v2_lose         u3a_lose
 #     define u3a_v2_malloc       u3a_malloc
 #     define u3a_v2_minimum      u3a_minimum
 #     define u3a_v2_outa         u3a_outa
diff --git a/pkg/noun/v2/hashtable.h b/pkg/noun/v2/hashtable.h
index be6ab9587c..09025fc19f 100644
--- a/pkg/noun/v2/hashtable.h
+++ b/pkg/noun/v2/hashtable.h
@@ -3,6 +3,7 @@
 
 #define u3h_v2_buck          u3h_buck
 #define u3h_v2_free          u3h_free
+#define u3h_v2_new           u3h_new
 #define u3h_v2_node          u3h_node
 #define u3h_v2_noun_to_slot  u3h_noun_to_slot
 #define u3h_v2_root          u3h_root
diff --git a/pkg/noun/v2/jets.c b/pkg/noun/v2/jets.c
index e70ef46abe..4b25c0e9d5 100644
--- a/pkg/noun/v2/jets.c
+++ b/pkg/noun/v2/jets.c
@@ -9,6 +9,18 @@
 #include "pkg/noun/v2/hashtable.h"
 #include "pkg/noun/v2/vortex.h"
 
+/* u3j_v2_reclaim(): clear ad-hoc persistent caches to reclaim memory.
+*/
+void
+u3j_v2_reclaim(void)
+{
+  //  clear the jet hank cache
+  //
+  u3h_v2_walk(u3R_v2->jed.han_p, u3j_v2_free_hank);
+  u3h_v2_free(u3R_v2->jed.han_p);
+  u3R_v2->jed.han_p = u3h_v2_new();
+}
+
 /* u3j_v2_rewrite_compact(): rewrite jet state for compaction.
  *
  * NB: u3R_v2->jed.han_p *must* be cleared (currently via u3j_v2_reclaim above)
diff --git a/pkg/noun/v2/jets.h b/pkg/noun/v2/jets.h
index a596170f60..281c5d62be 100644
--- a/pkg/noun/v2/jets.h
+++ b/pkg/noun/v2/jets.h
@@ -3,17 +3,30 @@
 #ifndef U3_JETS_V2_H
 #define U3_JETS_V2_H
 
+#include "pkg/noun/allocate.h"
+#include "pkg/noun/jets.h"
+
+
   /**  Aliases.
   **/
+#     define  u3j_v2_core       u3j_core
 #     define  u3j_v2_fink       u3j_fink
 #     define  u3j_v2_fist       u3j_fist
+#     define  u3j_v2_hank       u3j_hank
+#     define  u3j_v2_free_hank  u3j_free_hank
+#     define  u3j_v2_harm       u3j_harm
 #     define  u3j_v2_rite       u3j_rite
-#     define  u3j_v2_rite_lose  u3j_rite_lose
 #     define  u3j_v2_site       u3j_site
+#     define  u3j_v2_rite_lose  u3j_rite_lose
 #     define  u3j_v2_site_lose  u3j_site_lose
 
   /**  Functions.
   **/
+    /* u3j_v2_reclaim(): clear ad-hoc persistent caches to reclaim memory.
+    */
+      void
+      u3j_v2_reclaim(void);
+
     /* u3j_v2_rewrite_compact(): rewrite jet state for compaction.
     */
       void
diff --git a/pkg/noun/v2/manage.h b/pkg/noun/v2/manage.h
index 998a37cc65..1d03b97809 100644
--- a/pkg/noun/v2/manage.h
+++ b/pkg/noun/v2/manage.h
@@ -3,10 +3,9 @@
 #ifndef U3_MANAGE_V2_H
 #define U3_MANAGE_V2_H
 
-    /** System management.
+    /**  System management.
     **/
       /* u3m_v2_migrate: perform pointer compression loom migration if necessary.
-         ver_w - target version
       */
         void
         u3m_v2_migrate();
diff --git a/pkg/noun/v2/nock.c b/pkg/noun/v2/nock.c
index 95a011e005..d8e447a417 100644
--- a/pkg/noun/v2/nock.c
+++ b/pkg/noun/v2/nock.c
@@ -1,11 +1,9 @@
 /// @file
 
-#include "pkg/noun/nock.h"
 #include "pkg/noun/v2/nock.h"
 
 #include "pkg/noun/v2/allocate.h"
 #include "pkg/noun/v2/hashtable.h"
-#include "pkg/noun/v2/vortex.h"
 
 /* u3n_v2_rewrite_compact(): rewrite the bytecode cache for compaction.
  *
diff --git a/pkg/noun/v2/nock.h b/pkg/noun/v2/nock.h
index eddc3d2074..13432f384b 100644
--- a/pkg/noun/v2/nock.h
+++ b/pkg/noun/v2/nock.h
@@ -3,13 +3,16 @@
 #ifndef U3_NOCK_V2_H
 #define U3_NOCK_V2_H
 
+#include "pkg/noun/nock.h"
+
+#include "types.h"
+
   /**  Aliases.
   **/
-#define     u3n_v2_free  u3n_free
-#define     u3n_v2_prog  u3n_prog
+#     define  u3n_v2_memo     u3n_memo
+#     define  u3n_v2_prog     u3n_prog
+#     define  u3n_v2_reclaim  u3n_reclaim
 
-  /**  Functions.
-  **/
     /* u3n_v2_rewrite_compact(): rewrite bytecode cache for compaction.
      */
       void
diff --git a/pkg/noun/v3/allocate.h b/pkg/noun/v3/allocate.h
new file mode 100644
index 0000000000..fb9fa73015
--- /dev/null
+++ b/pkg/noun/v3/allocate.h
@@ -0,0 +1,16 @@
+#ifndef U3_ALLOCATE_V3_H
+#define U3_ALLOCATE_V3_H
+
+#include "pkg/noun/allocate.h"
+
+#include "pkg/noun/v3/manage.h"
+#include "options.h"
+
+  /**  Aliases.
+  **/
+#     define u3R_v3              u3a_Road
+#     define u3a_v3_balign       u3a_balign
+#     define u3a_v3_road         u3a_road
+#     define u3a_v3_walign       u3a_walign
+
+#endif /* ifndef U3_ALLOCATE_V3_H */
diff --git a/pkg/noun/v3/hashtable.h b/pkg/noun/v3/hashtable.h
new file mode 100644
index 0000000000..7ad854b91c
--- /dev/null
+++ b/pkg/noun/v3/hashtable.h
@@ -0,0 +1,8 @@
+#ifndef U3_HASHTABLE_V3_H
+#define U3_HASHTABLE_V3_H
+
+#define u3h_v3_new_cache     u3h_new_cache
+
+#include "pkg/noun/hashtable.h"
+
+#endif /* U3_HASHTABLE_V3_H */
diff --git a/pkg/noun/v3/manage.c b/pkg/noun/v3/manage.c
new file mode 100644
index 0000000000..a9236ffa80
--- /dev/null
+++ b/pkg/noun/v3/manage.c
@@ -0,0 +1,111 @@
+/// @file
+
+#include "pkg/noun/v3/manage.h"
+
+#include "pkg/noun/v2/jets.h"
+#include "pkg/noun/v2/nock.h"
+#include "pkg/noun/v2/vortex.h"
+
+#include "pkg/noun/v3/allocate.h"
+#include "pkg/noun/v3/hashtable.h"
+#include "pkg/noun/version.h"
+#include "pkg/noun/v3/vortex.h"
+#include <v2/allocate.h>
+
+/* u3m_v3_migrate: perform loom migration if necessary.
+*/
+void
+u3m_v3_migrate()
+{
+  fprintf(stderr, "loom: memoization migration running...\r\n");
+
+
+  c3_w ver_w = *(u3_Loom + u3C.wor_i - 1);
+  c3_w *mem_w = u3_Loom + u3a_v3_walign;
+  c3_w  len_w = u3C.wor_i - u3a_v3_walign;
+  c3_w  suz_w = c3_wiseof(u3v_v2_home);
+  c3_w *mut_w = c3_align(mem_w + len_w - suz_w, u3a_v3_balign, C3_ALGLO);
+
+  //  old road
+  u3v_v2_home* hum_u = (u3v_v2_home*)mut_w;
+  u3a_v2_road* rud_u = &hum_u->rod_u;
+  size_t ruz_t = sizeof(u3a_v2_road);
+
+  //  set v2 globals
+  u3H_v2 = (void *)mut_w;
+  u3R_v2 = &u3H_v2->rod_u;
+  u3R_v2->cap_p = u3R_v2->mat_p = u3a_v2_outa(u3H_v2);
+  u3H = (u3v_home*)u3H_v2;
+  u3R = (u3a_road*)u3R_v2;
+
+  //  free bytecode caches in old road
+  u3j_v2_reclaim();
+  u3n_v2_reclaim();
+
+  //  new home, new road
+  u3v_v3_home hom_u = {0};
+  u3a_v3_road rod_u = {0};
+
+  //  copy members, one-by-one, from old road to new road
+  rod_u.par_p = rud_u->par_p;
+  rod_u.kid_p = rud_u->kid_p;
+  rod_u.nex_p = rud_u->nex_p;
+
+  rod_u.cap_p = rud_u->cap_p;
+  rod_u.hat_p = rud_u->hat_p;
+  rod_u.mat_p = rud_u->mat_p;
+  rod_u.rut_p = rud_u->rut_p;
+  rod_u.ear_p = rud_u->ear_p;
+
+  //  no need to zero-out fut_w
+  //  no need to do anything with esc
+
+  rod_u.how.fag_w = rud_u->how.fag_w;
+
+  memcpy(rod_u.all.fre_p, rud_u->all.fre_p, sizeof(rud_u->all.fre_p));
+  rod_u.all.cel_p = rud_u->all.cel_p;
+  rod_u.all.fre_w = rud_u->all.fre_w;
+  rod_u.all.max_w = rud_u->all.max_w;
+
+  rod_u.jed.hot_p = rud_u->jed.hot_p;
+  rod_u.jed.war_p = rud_u->jed.war_p;
+  rod_u.jed.cod_p = rud_u->jed.cod_p;
+  rod_u.jed.han_p = rud_u->jed.han_p;
+  rod_u.jed.bas_p = rud_u->jed.bas_p;
+
+  rod_u.byc.har_p = rud_u->byc.har_p;
+
+  rod_u.ski.gul = rud_u->ski.gul;
+
+  rod_u.bug.tax = rud_u->bug.tax;
+  rod_u.bug.mer = rud_u->bug.mer;
+
+  rod_u.pro.nox_d = rud_u->pro.nox_d;
+  rod_u.pro.cel_d = rud_u->pro.cel_d;
+  rod_u.pro.don   = rud_u->pro.don;
+  rod_u.pro.trace = rud_u->pro.trace;
+  rod_u.pro.day   = rud_u->pro.day;
+
+  rod_u.cax.har_p = rud_u->cax.har_p;
+
+  //  prepare the new home, update the version
+  hom_u.arv_u = hum_u->arv_u;
+  hom_u.rod_u = rod_u;
+  hom_u.ver_w = U3V_VER3;
+
+  //  place the new home over the old one
+  c3_w  siz_w = c3_wiseof(u3v_v3_home);
+  c3_w *mat_w = c3_align(mem_w + len_w - siz_w, u3a_v3_balign, C3_ALGLO);
+  memcpy(mat_w, &hom_u, sizeof(u3v_v3_home));
+
+  //  set globals
+  u3H_v3 = (void*)mat_w;
+  u3R_v3 = &u3H_v3->rod_u;
+  u3H = (u3v_home*)u3H_v3;
+  u3R = (u3a_road*)u3R_v3;
+
+  //  initialize persistent cache
+  u3R_v3->cax.per_p = u3h_v3_new_cache(u3C.per_w);
+
+  fprintf(stderr, "loom: memoization migration done\r\n");
+}
diff --git a/pkg/noun/v3/manage.h b/pkg/noun/v3/manage.h
new file mode 100644
index 0000000000..5745a6316b
--- /dev/null
+++ b/pkg/noun/v3/manage.h
@@ -0,0 +1,13 @@
+/// @file
+
+#ifndef U3_MANAGE_V3_H
+#define U3_MANAGE_V3_H
+
+    /** System management.
+    **/
+      /* u3m_v3_migrate: perform memoization loom migration if necessary.
+      */
+        void
+        u3m_v3_migrate();
+
+#endif /* ifndef U3_MANAGE_V3_H */
diff --git a/pkg/noun/v3/vortex.c b/pkg/noun/v3/vortex.c
new file mode 100644
index 0000000000..7f2a9e6569
--- /dev/null
+++ b/pkg/noun/v3/vortex.c
@@ -0,0 +1,5 @@
+/// @file
+
+#include "pkg/noun/v3/vortex.h"
+
+u3v_v3_home* u3v_v3_Home;
diff --git a/pkg/noun/v3/vortex.h b/pkg/noun/v3/vortex.h
new file mode 100644
index 0000000000..58443a79a3
--- /dev/null
+++ b/pkg/noun/v3/vortex.h
@@ -0,0 +1,35 @@
+/// @file
+
+#ifndef U3_VORTEX_V3_H
+#define U3_VORTEX_V3_H
+
+#include "pkg/noun/vortex.h"
+
+#include "pkg/noun/v3/allocate.h"
+#include "pkg/noun/version.h"
+
+  /**  Aliases.
+  **/
+#     define     u3v_v3_arvo  u3v_arvo
+#     define     u3H_v3       u3v_Home
+#     define     u3A_v3       (&(u3H_v3)->arv_u)
+
+  /**  Data structures.
+  **/
+    /* u3v_v3_home: all internal (within image) state.
+    **       NB: version must be last for discriminability in north road
+    */
+      typedef struct _u3v_v3_home {
+        u3a_v3_road    rod_u;                //  storage state
+        u3v_v3_arvo    arv_u;                //  arvo state
+        u3v_version    ver_w;                //  version number
+      } u3v_v3_home;
+
+  /**  Functions.
+  **/
+    /* u3v_v3_rewrite_compact(): rewrite arvo kernel for compaction.
+    */
+      void
+      u3v_v3_rewrite_compact();
+
+#endif /* ifndef U3_VORTEX_V3_H */
diff --git a/pkg/noun/version.h b/pkg/noun/version.h
index f64d0a398e..bc81c83f5a 100644
--- a/pkg/noun/version.h
+++ b/pkg/noun/version.h
@@ -8,7 +8,8 @@ typedef c3_w       u3v_version;
 
 #define U3V_VER1   1
 #define U3V_VER2   2
-#define U3V_VERLAT U3V_VER2
+#define U3V_VER3   3
+#define U3V_VERLAT U3V_VER3
 
 /* EVENTS
  */
diff --git a/pkg/noun/zave.c b/pkg/noun/zave.c
index 0955af906c..596200f887 100644
--- a/pkg/noun/zave.c
+++ b/pkg/noun/zave.c
@@ -5,6 +5,7 @@
 #include "allocate.h"
 #include "hashtable.h"
 #include "imprison.h"
+#include "vortex.h"
 
 /* u3z_key(): construct a memo cache-key.  Arguments retained.
 */
@@ -34,30 +35,60 @@ u3z_key_5(c3_m fun, u3_noun one, u3_noun two, u3_noun tri, u3_noun qua, u3_noun
   return u3nc(fun, u3nq(u3k(one), u3k(two), u3k(tri), u3nc(u3k(qua), u3k(qin))));
 }
 
+/* _har(): get the memo cache for the given cid.
+*/
+static u3p(u3h_root)
+_har(u3a_road* rod_u, u3z_cid cid)
+{
+  switch ( cid ) {
+    case u3z_memo_toss:
+      return rod_u->cax.har_p;
+    case u3z_memo_keep:
+      return rod_u->cax.per_p;
+  }
+  u3_assert(0);
+}
+
 /* u3z_find(): find in memo cache.  Arguments retained.
 */
 u3_weak
-u3z_find(u3_noun key)
+u3z_find(u3z_cid cid, u3_noun key)
 {
-  return u3h_get(u3R->cax.har_p, key);
+  if ( u3z_memo_toss == cid ) {
+    return u3h_get(_har(u3R, cid), key);
+  }
+  else {
+    //  XX needs to be benchmarked (up vs. down search)
+    u3a_road* rod_u = &(u3H->rod_u);
+    while ( 1 ) {
+      u3_weak got = u3h_get(_har(rod_u, cid), key);
+      if ( u3_none != got ) {
+        return got;
+      }
+      if ( 0 == rod_u->kid_p ) {
+        return u3_none;
+      }
+      rod_u = u3to(u3a_road, rod_u->kid_p);
+    };
+  }
 }
 u3_weak
-u3z_find_m(c3_m fun, u3_noun one)
+u3z_find_m(u3z_cid cid, c3_m fun, u3_noun one)
 {
   u3_noun key = u3nc(fun, u3k(one));
   u3_weak val;
-
-  val = u3h_get(u3R->cax.har_p, key);
+  val = u3z_find(cid, key);
   u3z(key);
+
   return val;
 }
 
 /* u3z_save(): save in memo cache. TRANSFER key; RETAIN val
 */
 u3_noun
-u3z_save(u3_noun key, u3_noun val)
+u3z_save(u3z_cid cid, u3_noun key, u3_noun val)
 {
-  u3h_put(u3R->cax.har_p, key, u3k(val));
+  u3h_put(_har(u3R, cid), key, u3k(val));
   u3z(key);
   return val;
 }
@@ -65,28 +96,39 @@ u3z_save(u3_noun key, u3_noun val)
 /* u3z_save_m(): save in memo cache. Arguments retained.
 */
 u3_noun
-u3z_save_m(c3_m fun, u3_noun one, u3_noun val)
+u3z_save_m(u3z_cid cid, c3_m fun, u3_noun one, u3_noun val)
 {
   u3_noun key = u3nc(fun, u3k(one));
 
-  u3h_put(u3R->cax.har_p, key, u3k(val));
+  u3h_put(_har(u3R, cid), key, u3k(val));
   u3z(key);
   return val;
 }
 
-/* u3z_uniq(): uniquify with memo cache.
+/* u3z_uniq(): uniquify with memo cache. XX not used.
 */
 u3_noun
-u3z_uniq(u3_noun som)
+u3z_uniq(u3z_cid cid, u3_noun som)
 {
   u3_noun key = u3nc(c3__uniq, u3k(som));
-  u3_noun val = u3h_get(u3R->cax.har_p, key);
+  u3_noun val = u3h_get(_har(u3R, cid), key);
 
   if ( u3_none != val ) {
     u3z(key); u3z(som); return val;
   }
   else {
-    u3h_put(u3R->cax.har_p, key, u3k(som));
+    u3h_put(_har(u3R, cid), key, u3k(som));
     return som;
   }
 }
+
+/* u3z_reap(): promote memoization cache state.
+*/
+void
+u3z_reap(u3z_cid cid, u3p(u3h_root) har_p)
+{
+  u3_assert(u3z_memo_toss != cid);
+
+  u3h_uni(_har(u3R, cid), har_p);
+  u3h_free(har_p);
+}
diff --git a/pkg/noun/zave.h b/pkg/noun/zave.h
index 44f272da7c..feff83f664 100644
--- a/pkg/noun/zave.h
+++ b/pkg/noun/zave.h
@@ -12,10 +12,18 @@
   ***  and a noun argument to that (logical) function.  Functions
   ***  are predefined by C-level callers, but 0 means nock.
   ***
-  ***  The memo cache is within its road and dies when it falls.
-  ***
   ***  Memo functions RETAIN keys and transfer values.
   **/
+    /* u3z_cid: cache id
+    */
+      typedef enum {
+        u3z_memo_toss  = 0,
+        u3z_memo_keep  = 1,
+        // u3z_memo_ford  = 2,
+        // u3z_memo_ames  = 3,
+        // ...
+      } u3z_cid;
+
     /* u3z_key*(): construct a memo cache-key.  Arguments retained.
     */
       u3_noun u3z_key(c3_m, u3_noun);
@@ -26,20 +34,35 @@
 
     /* u3z_find*(): find in memo cache. Arguments retained
     */
-      u3_weak u3z_find(u3_noun key);
-      u3_weak u3z_find_m(c3_m fun_m, u3_noun one);
+      u3_weak u3z_find(u3z_cid cid, u3_noun key);
+      u3_weak u3z_find_m(u3z_cid cid, c3_m fun_m, u3_noun one);
 
     /* u3z_save(): save in memo cache. TRANSFER key; RETAIN val;
     */
-      u3_noun u3z_save(u3_noun key, u3_noun val);
+      u3_noun u3z_save(u3z_cid cid, u3_noun key, u3_noun val);
 
     /* u3z_save_m(): save in memo cache. Arguments retained
     */
-      u3_noun u3z_save_m(c3_m fun_m, u3_noun one, u3_noun val);
+      u3_noun u3z_save_m(u3z_cid cid, c3_m fun_m, u3_noun one, u3_noun val);
 
     /* u3z_uniq(): uniquify with memo cache.
     */
       u3_noun
-      u3z_uniq(u3_noun som);
+      u3z_uniq(u3z_cid cid, u3_noun som);
+
+    /* u3z_reap(): promote memoization cache state.
+    */
+      void
+      u3z_reap(u3z_cid cid, u3p(u3h_root) har_p);
+
+    /* u3z_free(): free memoization cache.
+    */
+      void
+      u3z_free(u3z_cid cid);
+
+    /* u3z_ream(): refresh after restoring from checkpoint.
+    */
+      void
+      u3z_ream(u3z_cid cid);
 
 #endif /* ifndef U3_ZAVE_H */
diff --git a/pkg/vere/BUILD.bazel b/pkg/vere/BUILD.bazel
index 76f8b47eca..f856ce0047 100644
--- a/pkg/vere/BUILD.bazel
+++ b/pkg/vere/BUILD.bazel
@@ -301,7 +301,7 @@ genrule(
 
     if check && sleep 10 && check; then
       echo "boot success"
-      lensa hood "+hood/exit"
+      lensa hood '+hood/exit'
       while [ -f ./pier/.vere.lock ]; do
         echo "waiting for pier to shut down"
         sleep 5
diff --git a/pkg/vere/lord.c b/pkg/vere/lord.c
index cf1dfcfba9..a63824ae9b 100644
--- a/pkg/vere/lord.c
+++ b/pkg/vere/lord.c
@@ -1160,10 +1160,11 @@ u3_lord_init(c3_c* pax_c, c3_w wag_w, c3_d key_d[4], u3_lord_cb cb_u)
   //  spawn new process and connect to it
   //
   {
-    c3_c* arg_c[11];
+    c3_c* arg_c[12];
     c3_c  key_c[256];
     c3_c  wag_c[11];
     c3_c  hap_c[11];
+    c3_c  per_c[11];
     c3_c  cev_c[11];
     c3_c  lom_c[11];
     c3_c  tos_c[11];
@@ -1179,6 +1180,8 @@ u3_lord_init(c3_c* pax_c, c3_w wag_w, c3_d key_d[4], u3_lord_cb cb_u)
 
     sprintf(hap_c, "%u", u3_Host.ops_u.hap_w);
 
+    sprintf(per_c, "%u", u3_Host.ops_u.per_w);
+
     sprintf(lom_c, "%u", u3_Host.ops_u.lom_y);
 
     sprintf(tos_c, "%u", u3C.tos_w);
@@ -1208,7 +1211,8 @@ u3_lord_init(c3_c* pax_c, c3_w wag_w, c3_d key_d[4], u3_lord_cb cb_u)
     }
 
     arg_c[9] = tos_c;
-    arg_c[10] = NULL;
+    arg_c[10] = per_c;
+    arg_c[11] = NULL;
 
     uv_pipe_init(u3L, &god_u->inn_u.pyp_u, 0);
     uv_timer_init(u3L, &god_u->out_u.tim_u);
diff --git a/pkg/vere/main.c b/pkg/vere/main.c
index f83d656e98..c35b7ff2e4 100644
--- a/pkg/vere/main.c
+++ b/pkg/vere/main.c
@@ -183,6 +183,9 @@ _main_init(void)
   u3_Host.ops_u.veb = c3n;
   u3_Host.ops_u.puf_c = "jam";
   u3_Host.ops_u.hap_w = 50000;
+  u3C.hap_w = u3_Host.ops_u.hap_w;
+  u3_Host.ops_u.per_w = 50000;
+  u3C.per_w = u3_Host.ops_u.per_w;
   u3_Host.ops_u.kno_w = DefaultKernel;
 
   u3_Host.ops_u.sap_w = 120;    /* aka 2 minutes */
@@ -247,6 +250,7 @@ _main_getopt(c3_i argc, c3_c** argv)
     { "loom",                required_argument, NULL, c3__loom },
     { "local",               no_argument,       NULL, 'L' },
     { "lite-boot",           no_argument,       NULL, 'l' },
+    { "keep-cache-limit",    required_argument, NULL, 'M' },
     { "replay-to",           required_argument, NULL, 'n' },
     { "profile",             no_argument,       NULL, 'P' },
     { "ames-port",           required_argument, NULL, 'p' },
@@ -279,7 +283,7 @@ _main_getopt(c3_i argc, c3_c** argv)
   };
 
   while ( -1 != (ch_i=getopt_long(argc, argv,
-                 "A:B:C:DF:G:H:I:J:K:LPRSX:Y:Z:ab:c:de:gi:jk:ln:p:qr:stu:vw:x",
+                 "A:B:C:DF:G:H:I:J:K:LM:PRSX:Y:Z:ab:c:de:gi:jk:ln:p:qr:stu:vw:x",
                  lop_u, &lid_i)) )
   {
     switch ( ch_i ) {
@@ -342,7 +346,7 @@ _main_getopt(c3_i argc, c3_c** argv)
           return c3n;
         } else {
           u3_Host.ops_u.sap_w = arg_w * 60;
-          if ( 0 == u3_Host.ops_u.sap_w) 
+          if ( 0 == u3_Host.ops_u.sap_w )
             return c3n;
         }
         break;
@@ -365,6 +369,7 @@ _main_getopt(c3_i argc, c3_c** argv)
         if ( c3n == _main_readw(optarg, 1000000000, &u3_Host.ops_u.hap_w) ) {
           return c3n;
         }
+        u3C.hap_w = u3_Host.ops_u.hap_w;
         break;
       }
       case 'c': {
@@ -412,6 +417,13 @@ _main_getopt(c3_i argc, c3_c** argv)
         u3_Host.ops_u.key_c = _main_repath(optarg);
         break;
       }
+      case 'M': {
+        if ( c3n == _main_readw(optarg, 1000000000, &u3_Host.ops_u.per_w) ) {
+          return c3n;
+        }
+        u3C.per_w = u3_Host.ops_u.per_w;
+        break;
+      }
       case 'n': {
         u3_Host.ops_u.til_c = strdup(optarg);
         break;
@@ -764,6 +776,7 @@ u3_ve_usage(c3_i argc, c3_c** argv)
     "-L, --local                   Local networking only\n",
     "    --loom                    Set loom to binary exponent (31 == 2GB)\n"
     "-l, --lite-boot               Most-minimal startup\n",
+    "-M, --keep-cache-limit LIMIT  Set persistent memo cache max size; 0 means default\n",
     "-n, --replay-to NUMBER        Replay up to event\n",
     "-P, --profile                 Profiling\n",
     "-p, --ames-port PORT          Set the ames port to bind to\n",
@@ -1075,6 +1088,8 @@ _cw_serf_commence(c3_i argc, c3_c* argv[])
     exit(1);
   }
 
+  //  XX use named arguments and getopt
+
   c3_d       eve_d = 0;
   uv_loop_t* lup_u = u3_Host.lup_u = uv_default_loop();
   c3_c*      dir_c = argv[2];
@@ -1086,6 +1101,7 @@ _cw_serf_commence(c3_i argc, c3_c* argv[])
   c3_c*      eve_c = argv[7];
   c3_c*      eph_c = argv[8];
   c3_c*      tos_c = argv[9];
+  c3_c*      per_c = argv[10];
   c3_w       tos_w;
 
   _cw_init_io(lup_u);
@@ -1110,7 +1126,8 @@ _cw_serf_commence(c3_i argc, c3_c* argv[])
     //  XX check return
     //
     sscanf(wag_c, "%" SCNu32, &u3C.wag_w);
-    sscanf(hap_c, "%" SCNu32, &u3_Host.ops_u.hap_w);
+    sscanf(hap_c, "%" SCNu32, &u3C.hap_w);
+    sscanf(per_c, "%" SCNu32, &u3C.per_w);
     sscanf(lom_c, "%" SCNu32, &lom_w);
 
     if ( 1 != sscanf(tos_c, "%" SCNu32, &u3C.tos_w) ) {
diff --git a/pkg/vere/pier.c b/pkg/vere/pier.c
index 1e39d14ef4..8e54dbb37e 100644
--- a/pkg/vere/pier.c
+++ b/pkg/vere/pier.c
@@ -675,8 +675,8 @@ _pier_wyrd_fail(u3_pier* pir_u, u3_ovum* egg_u, u3_noun lud)
 //  XX organizing version constants
 //
 #define VERE_NAME  "vere"
-#define VERE_ZUSE  412
-#define VERE_LULL  323
+#define VERE_ZUSE  411
+#define VERE_LULL  322
 
 /* _pier_wyrd_aver(): check for %wend effect and version downgrade. RETAIN
 */
diff --git a/pkg/vere/vere.h b/pkg/vere/vere.h
index cef16810b6..2bf976c1dd 100644
--- a/pkg/vere/vere.h
+++ b/pkg/vere/vere.h
@@ -263,7 +263,7 @@
         c3_o    abo;                        //  -a, abort aggressively
         c3_c*   pil_c;                      //  -B, bootstrap from
         c3_c*   bin_c;                      //  -b, http server bind ip
-        c3_w    hap_w;                      //  -C, cap memo cache
+        c3_w    hap_w;                      //  -C, cap transient memo cache
         c3_o    dry;                        //  -D, dry compute, no checkpoint
         c3_o    dem;                        //  -d, daemon
         c3_c*   eth_c;                      //  -e, ethereum node url
@@ -281,6 +281,7 @@
         c3_o    lit;                        //  -l, lite mode
         c3_y    lom_y;                      //      loom bex
         c3_y    lut_y;                      //      urth-loom bex
+        c3_w    per_w;                      //  -M, cap persistent memo cache
         c3_c*   til_c;                      //  -n, play till eve_d
         c3_o    pro;                        //  -P, profile
         c3_s    per_s;                      //      http port