diff --git a/ueforth/Makefile b/ueforth/Makefile
index 74805e5..441b764 100644
--- a/ueforth/Makefile
+++ b/ueforth/Makefile
@@ -124,13 +124,15 @@ $(GEN):
 POSIX_BOOT =  common/boot.fs common/vocabulary.fs common/hide_calls.fs common/ansi.fs \
               posix/posix.fs posix/posix_highlevel.fs posix/termios.fs common/locals.fs \
               common/utils.fs common/highlevel.fs common/filetools.fs posix/posix_desktop.fs \
-              common/tasks.fs common/streams.fs common/blocks.fs posix/args.fs
+              common/tasks.fs common/streams.fs common/blocks.fs posix/args.fs \
+              common/fini.fs
 $(GEN)/posix_boot.h: common/source_to_string.js $(POSIX_BOOT) | $(GEN)
 	echo "ok" | cat $(POSIX_BOOT) - | $< boot $(VERSION) $(REVISION) >$@
 
 WINDOWS_BOOT = common/boot.fs common/vocabulary.fs common/hide_calls.fs common/ansi.fs \
                windows/windows.fs windows/windows_highlevel.fs common/highlevel.fs \
-               common/utils.fs common/tasks.fs common/streams.fs common/blocks.fs common/locals.fs
+               common/utils.fs common/tasks.fs common/streams.fs common/blocks.fs common/locals.fs \
+               common/fini.fs
 $(GEN)/windows_boot.h: common/source_to_string.js $(WINDOWS_BOOT) | $(GEN)
 	echo "ok" | cat $(WINDOWS_BOOT) - | $< boot $(VERSION) $(REVISION) >$@
 
@@ -141,7 +143,8 @@ ARDUINO_BOOT = common/boot.fs common/vocabulary.fs \
                common/tasks.fs common/streams.fs arduino/arduino_server.fs \
                arduino/arduino_bterm.fs \
                arduino/esp_camera.fs common/blocks.fs \
-               arduino/autoboot.fs
+               arduino/autoboot.fs \
+               common/fini.fs
 $(GEN)/arduino_boot.h: common/source_to_string.js $(ARDUINO_BOOT) | $(GEN)
 	echo "ok" | cat $(ARDUINO_BOOT) - | $< boot $(VERSION) $(REVISION) >$@
 
diff --git a/ueforth/arduino/autoboot.fs b/ueforth/arduino/autoboot.fs
index 9377f60..00faf4d 100644
--- a/ueforth/arduino/autoboot.fs
+++ b/ueforth/arduino/autoboot.fs
@@ -5,6 +5,5 @@ internals definitions
 
 ( Check for autoexec.fs and run if present )
 : autoexec ( a n -- ) s" /spiffs/autoexec.fs" ['] included catch 2drop drop ;
-' autoexec
+' autoexec ( leave on the stack for fini.fs )
 forth definitions
-execute
diff --git a/ueforth/common/core.h b/ueforth/common/core.h
index db2d1bf..07767f3 100644
--- a/ueforth/common/core.h
+++ b/ueforth/common/core.h
@@ -130,7 +130,7 @@ static cell_t *forth_run(cell_t *initrp);
 
 static void forth_init(int argc, char *argv[], void *heap,
                          const char *src, cell_t src_len) {
-  g_sys.heap = (cell_t *) heap + 4;  // Leave a little room.
+  g_sys.heap = ((cell_t *) heap) + 4;  // Leave a little room.
   cell_t *sp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
   cell_t *rp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
 
diff --git a/ueforth/common/filetools.fs b/ueforth/common/filetools.fs
index d9bc8ba..3790b58 100644
--- a/ueforth/common/filetools.fs
+++ b/ueforth/common/filetools.fs
@@ -3,3 +3,27 @@
   >r r@ write-file if r> drop ." failed write-file" exit then
   r> close-file drop
 ;
+
+internals definitions
+( Leave some room for growth of starting system. )
+$4000 constant growth-gap
+here growth-gap + growth-gap 1- + growth-gap 1- invert and constant saving-base
+: park-heap ( -- a ) saving-base ;
+: park-forth ( -- a ) saving-base cell+ ;
+forth definitions also internals
+
+: save ( "name" -- )
+  'heap @ park-heap !
+  forth-wordlist @ park-forth !
+  bl parse w/o create-file throw >r
+  saving-base here over - r@ write-file throw
+  r> close-file throw ;
+
+: restore ( "name" -- )
+  bl parse r/o open-file throw >r
+  saving-base r@ file-size throw r@ read-file throw drop
+  r> close-file throw
+  park-heap @ 'heap !
+  park-forth @ forth-wordlist ! ;
+
+only forth definitions
diff --git a/ueforth/common/fini.fs b/ueforth/common/fini.fs
new file mode 100644
index 0000000..c86e62e
--- /dev/null
+++ b/ueforth/common/fini.fs
@@ -0,0 +1,7 @@
+internals
+( Bring a forth to the top of the vocabulary. )
+transfer forth
+( Move heap to save point, with a gap. )
+saving-base 16 cells + 'heap !
+forth
+execute ( assumes an xt for autoboot is on the dstack )
diff --git a/ueforth/posix/args.fs b/ueforth/posix/args.fs
index 0d49182..46b2e31 100644
--- a/ueforth/posix/args.fs
+++ b/ueforth/posix/args.fs
@@ -1,6 +1,5 @@
 ( Include first argument if any )
 internals definitions
 : optional-args argc 2 < if exit then 1 argv included ;
-' optional-args
+' optional-args ( leave on dstack for fini.fs )
 forth definitions
-execute
diff --git a/ueforth/posix/posix_main.c b/ueforth/posix/posix_main.c
index 2a1ce03..a7fdaf2 100644
--- a/ueforth/posix/posix_main.c
+++ b/ueforth/posix/posix_main.c
@@ -6,7 +6,7 @@
 #include "common/calls.h"
 
 #define HEAP_SIZE (10 * 1024 * 1024)
-#define STACK_SIZE (16 * 1024)
+#define STACK_SIZE (64 * 1024)
 
 #define PLATFORM_OPCODE_LIST \
   Y(DLSYM, tos = (cell_t) dlsym(a1, a0); --sp) \
diff --git a/ueforth/windows/windows.fs b/ueforth/windows/windows.fs
index 22787e1..989238c 100644
--- a/ueforth/windows/windows.fs
+++ b/ueforth/windows/windows.fs
@@ -147,3 +147,4 @@ forth
 
 ( Setup entry )
 : ok   ." uEforth v{{VERSION}} - rev {{REVISION}}" cr prompt refill drop quit ;
+' forth ( leave on stack for fini.fs )