diff --git a/C/c_interface.c b/C/c_interface.c
index c4c922dfa..dabd21bd8 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -3172,7 +3172,11 @@ YAP_Init(YAP_init_args *yap_init)
 #endif /* YAPOR || TABLING */
 #ifdef YAPOR
     Yap_init_yapor_workers();
+#if YAPOR_THREADS
+    if (Yap_thread_self() != 0) {
+#else
     if (worker_id != 0) {
+#endif
 #if defined(YAPOR_COPY) || defined(YAPOR_SBA)
       /*
 	In the SBA we cannot just happily inherit registers
@@ -3390,6 +3394,9 @@ YAP_Reset(void)
   /* the first real choice-point will also have AP=FAIL */ 
   /* always have an empty slots for people to use */
   P = CP = YESCODE;
+  // ensure that we have slots where we need them
+  LOCAL_CurSlot = 0;
+  Yap_StartSlots( PASS_REGS1 );
   RECOVER_MACHINE_REGS();
   return res;
 }
diff --git a/C/grow.c b/C/grow.c
index 30e828b64..4b39362f5 100755
--- a/C/grow.c
+++ b/C/grow.c
@@ -147,6 +147,16 @@ SetHeapRegs(int copying_threads USES_REGS)
     LOCAL_OpenArray = PtoGloAdjust(LOCAL_OpenArray);
   if (B)
     B = ChoicePtrAdjust(B);
+#ifdef YAPOR_THREADS
+  {
+    choiceptr cpt;
+    cpt = Get_LOCAL_top_cp();
+    if (cpt) {
+      //      cpt = ChoicePtrAdjust( cpt );
+      Set_LOCAL_top_cp( cpt );
+    }
+  }
+#endif
 #ifdef TABLING
   if (B_FZ)
     B_FZ = ChoicePtrAdjust(B_FZ);
@@ -1899,11 +1909,59 @@ Yap_CopyThreadStacks(int worker_q, int worker_p, int incremental)
   /* make sure both stacks have same size */
   Int p_size = REMOTE_ThreadHandle(worker_p).ssize+REMOTE_ThreadHandle(worker_p).tsize;
   Int q_size = REMOTE_ThreadHandle(worker_q).ssize+REMOTE_ThreadHandle(worker_q).tsize;
-  if (p_size != q_size) {
-    if (!(REMOTE_ThreadHandle(worker_q).stack_address = realloc(REMOTE_ThreadHandle(worker_q).stack_address,p_size*K1))) {
-      exit(1);
+   if (p_size != q_size) {
+    UInt start_growth_time, growth_time;
+    int gc_verbose;
+    size_t ssiz = REMOTE_ThreadHandle(worker_q).ssize*K1;
+    size_t tsiz = REMOTE_ThreadHandle(worker_q).tsize*K1;
+    size_t diff = (REMOTE_ThreadHandle(worker_p).ssize-REMOTE_ThreadHandle(worker_q).ssize)*K1;
+    char *oldq = (char *)REMOTE_ThreadHandle(worker_q).stack_address, *newq;
+
+    if (!(newq = REMOTE_ThreadHandle(worker_q).stack_address = realloc(REMOTE_ThreadHandle(worker_q).stack_address,p_size*K1))) {
+      Yap_Error(OUT_OF_STACK_ERROR,TermNil,"cannot expand slave thread to match master thread");
+    }
+    start_growth_time = Yap_cputime();
+    gc_verbose = Yap_is_gc_verbose();
+    LOCAL_stack_overflows++;
+    if (gc_verbose) {
+#if  defined(YAPOR) || defined(THREADS)
+      fprintf(GLOBAL_stderr, "%% Worker Id %d:\n", worker_id);
+#endif
+      fprintf(GLOBAL_stderr, "%% Stack Overflow %d\n", LOCAL_stack_overflows);
+      fprintf(GLOBAL_stderr, "%%   Stack: %8ld cells (%p-%p)\n", (unsigned long int)(LCL0-(CELL *)LOCAL_GlobalBase),LOCAL_GlobalBase,LCL0);
+      fprintf(GLOBAL_stderr, "%%   Trail:%8ld cells (%p-%p)\n",
+	      (unsigned long int)(TR-(tr_fr_ptr)LOCAL_TrailBase),LOCAL_TrailBase,TR);
+      fprintf(GLOBAL_stderr, "%% Growing the stacks %ld bytes\n", diff);
+    }
+    LOCAL_GDiff = LOCAL_GDiff0 = LOCAL_DelayDiff = LOCAL_BaseDiff = (newq-oldq);
+    LOCAL_TrDiff = LOCAL_LDiff = diff + LOCAL_GDiff;
+    LOCAL_XDiff = LOCAL_HDiff = 0;
+    LOCAL_GSplit = NULL;
+    YAPEnterCriticalSection();
+    SetHeapRegs(FALSE PASS_REGS);
+    {
+        choiceptr imageB; 
+
+	LOCAL_OldLCL0 = LCL0;
+	LCL0 = REMOTE_ThreadHandle(0).current_yaam_regs->LCL0_;
+	imageB = Get_GLOBAL_root_cp();
+	/* we know B */
+	B->cp_tr = TR = 
+	  (tr_fr_ptr)((CELL)(imageB->cp_tr)+((CELL)LOCAL_OldLCL0-(CELL)LCL0));
+	LCL0 = LOCAL_OldLCL0;
+	B->cp_h = H0;
+	B->cp_ap = GETWORK;
+	B->cp_or_fr = GLOBAL_root_or_fr;
+    }
+    YAPLeaveCriticalSection();
+    growth_time = Yap_cputime()-start_growth_time;
+    LOCAL_total_stack_overflow_time += growth_time;
+    if (gc_verbose) {
+      fprintf(GLOBAL_stderr, "%%   took %g sec\n", (double)growth_time/1000);
+      fprintf(GLOBAL_stderr, "%% Total of %g sec expanding stacks \n", (double)LOCAL_total_stack_overflow_time/1000);
     }
   }
+
   REMOTE_ThreadHandle(worker_q).ssize = REMOTE_ThreadHandle(worker_p).ssize;
   REMOTE_ThreadHandle(worker_q).tsize = REMOTE_ThreadHandle(worker_p).tsize;
   /* compute offset indicators */
diff --git a/C/load_foreign.c b/C/load_foreign.c
index 937c89f26..5a5f07b5f 100755
--- a/C/load_foreign.c
+++ b/C/load_foreign.c
@@ -83,7 +83,9 @@ p_load_foreign( USES_REGS1 )
   
   /* call the OS specific function for dynamic loading */
   if(Yap_LoadForeign(ofiles,libs,InitProcName,&InitProc)==LOAD_SUCCEEDED) {
+    Int CurSlot =   Yap_StartSlots( PASS_REGS1 );
     (*InitProc)();
+    LOCAL_CurSlot = CurSlot;
     returncode = TRUE;
   }
   
diff --git a/C/stdpreds.c b/C/stdpreds.c
index a150cc445..c5f6ca20d 100644
--- a/C/stdpreds.c
+++ b/C/stdpreds.c
@@ -1666,15 +1666,15 @@ p_access_yap_flags( USES_REGS1 )
     tout = TermNil;
     if (IsMode_LocalTrie(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomLocalTrie), tout);
-    else // if (IsMode_GlobalTrie(yap_flags[flag]))
+    else if (IsMode_GlobalTrie(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomGlobalTrie), tout);
     if (IsMode_LoadAnswers(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomLoadAnswers), tout);
-    else // if (IsMode_ExecAnswers(yap_flags[flag]))
+    else if (IsMode_ExecAnswers(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomExecAnswers), tout);
     if (IsMode_Local(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomLocal), tout);
-    else // if (IsMode_Batched(yap_flags[flag]))
+    else if (IsMode_Batched(yap_flags[flag]))
       tout = MkPairTerm(MkAtomTerm(AtomBatched), tout);
 #else
     tout = MkAtomTerm(AtomFalse);
diff --git a/C/text.c b/C/text.c
index 2f570c5bd..a71e3f7c3 100644
--- a/C/text.c
+++ b/C/text.c
@@ -463,14 +463,14 @@ read_Text( void *buf, seq_tv_t *inp, encoding_t *enc, int *minimal, size_t *leng
 #endif
   case YAP_STRING_CHARS:
     *enc = YAP_CHAR;
-    if (inp->sz)
+    if (inp->type & YAP_STRING_NCHARS)
       *lengp = inp->sz;
     else
       *lengp = strlen(inp->val.c);
     return (void *)inp->val.c;
   case YAP_STRING_WCHARS:
     *enc = YAP_WCHAR;
-    if (inp->sz)
+    if (inp->type & YAP_STRING_NCHARS)
       *lengp = inp->sz;
     else
       *lengp = wcslen(inp->val.w);
diff --git a/C/threads.c b/C/threads.c
index 051e0ef6c..435c4501e 100755
--- a/C/threads.c
+++ b/C/threads.c
@@ -127,7 +127,7 @@ store_specs(int new_worker_id, UInt ssize, UInt tsize, UInt sysize, Term *tpgoal
     REMOTE_c_output_stream(new_worker_id) = REMOTE_c_output_stream(0);
     REMOTE_c_error_stream(new_worker_id) = REMOTE_c_error_stream(0);
   }
-  pm = (ssize + tsize)*1024;
+  pm = (ssize + tsize)*K1;
   if (!(REMOTE_ThreadHandle(new_worker_id).stack_address = malloc(pm))) {
     return FALSE;
   }
diff --git a/H/YapText.h b/H/YapText.h
index 24768605a..10ff66475 100644
--- a/H/YapText.h
+++ b/H/YapText.h
@@ -294,6 +294,7 @@ Yap_CharsToAtom( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_ATOM;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -307,6 +308,7 @@ Yap_CharsToListOfAtoms( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_ATOMS;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -320,6 +322,7 @@ Yap_CharsToListOfCodes( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -333,6 +336,7 @@ Yap_CharsToString( const char *s USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   out.type = YAP_STRING_STRING;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -346,6 +350,7 @@ Yap_CharsToTDQ( const char *s, Term mod USES_REGS )
   seq_tv_t inp, out;
 
   inp.val.c = s;
+  inp.sz = 0;
   inp.type = YAP_STRING_CHARS;
   inp.mod = mod;
   out.type = mod_to_type(mod PASS_REGS);
@@ -689,7 +694,7 @@ static inline Atom
 Yap_StringToAtom(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOM;
@@ -702,7 +707,7 @@ static inline Atom
 Yap_StringSWIToAtom(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_ATOMS_CODES|YAP_STRING_TERM;
   out.type = YAP_STRING_ATOM;
@@ -715,7 +720,7 @@ static inline size_t
 Yap_StringToAtomic(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
@@ -728,7 +733,7 @@ static inline size_t
 Yap_StringToLength(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_LENGTH;
@@ -741,7 +746,7 @@ static inline size_t
 Yap_StringToListOfAtoms(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_ATOMS;
@@ -754,7 +759,7 @@ static inline size_t
 Yap_StringSWIToListOfAtoms(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.val.t = t0;
   inp.type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_ATOMS_CODES|YAP_STRING_TERM;
   out.type = YAP_STRING_ATOMS;
@@ -768,7 +773,7 @@ Yap_StringToListOfCodes(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.t = t0;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -793,7 +798,7 @@ Yap_StringToNumber(Term t0 USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.t = t0;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_STRING;
   out.type = YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -806,7 +811,7 @@ Yap_WCharsToListOfCodes(const wchar_t *s USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.w = s;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_WCHARS;
   out.type = YAP_STRING_CODES;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -821,7 +826,7 @@ Yap_WCharsToTDQ( wchar_t *s, Term mod USES_REGS )
 
   inp.val.w = s;
   inp.type = YAP_STRING_WCHARS;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.mod = mod;
   out.type = mod_to_type(mod PASS_REGS);
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -834,7 +839,7 @@ Yap_WCharsToString(const wchar_t *s USES_REGS)
 {
   seq_tv_t inp, out;
   inp.val.w = s;
-  inp.sz = -1;
+  inp.sz = 0;
   inp.type = YAP_STRING_WCHARS;
   out.type = YAP_STRING_STRING;
   if (!Yap_CVT_Text(&inp, &out PASS_REGS))
@@ -848,10 +853,10 @@ Yap_ConcatAtoms(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_ATOM;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_ATOM;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_ATOM;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return NULL;
@@ -864,10 +869,10 @@ Yap_ConcatAtomics(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_STRING|YAP_STRING_ATOM|YAP_STRING_INT|YAP_STRING_FLOAT|YAP_STRING_BIG|YAP_STRING_TERM;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_ATOM;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return NULL;
@@ -880,10 +885,10 @@ Yap_ConcatStrings(Term t1, Term t2 USES_REGS)
   seq_tv_t inpv[2], out;
   inpv[0].val.t = t1;
   inpv[0].type = YAP_STRING_STRING;
-  inpv[0].sz = -1;
+  inpv[0].sz = 0;
   inpv[1].val.t = t2;
   inpv[1].type = YAP_STRING_STRING;
-  inpv[1].sz = -1;
+  inpv[1].sz = 0;
   out.type = YAP_STRING_STRING;
   if (!Yap_Concat_Text(2, inpv, &out PASS_REGS))
     return 0L;
@@ -900,11 +905,11 @@ Yap_SpliceAtom(Term t1, Atom ats[], size_t cut, size_t max USES_REGS)
   cuts[1] = max;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, cuts, &inp, NULL, outv PASS_REGS))
     return NULL;
   ats[0] = outv[0].val.a;
@@ -918,13 +923,13 @@ Yap_SubtractHeadAtom(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
   outv[0].val.t = th;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
   outv[1].val.t = 0;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
     return NULL;
   return outv[1].val.a;
@@ -937,10 +942,10 @@ Yap_SubtractTailAtom(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_ATOM;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_ATOM;
   outv[0].val.t = 0;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_ATOM;
   outv[1].val.t = th;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
@@ -955,10 +960,10 @@ Yap_SpliceString(Term t1, Term ts[], size_t cut, size_t max USES_REGS)
   size_t cuts[2];
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[1].type = YAP_STRING_STRING;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   cuts[0] = cut;
   cuts[1] = max;
   if (!Yap_Splice_Text(2, cuts, &inp, NULL, outv PASS_REGS))
@@ -974,13 +979,13 @@ Yap_SubtractHeadString(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[0].val.t = th;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_STRING;
   outv[1].val.t = 0;
-  outv[1].sz = -1;
+  outv[1].sz = 0;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
     return 0L;
   return outv[1].val.t;
@@ -992,10 +997,10 @@ Yap_SubtractTailString(Term t1, Term th USES_REGS)
   seq_tv_t outv[2], inp;
   inp.type = YAP_STRING_STRING;
   inp.val.t = t1;
-  inp.sz = -1;
+  inp.sz = 0;
   outv[0].type = YAP_STRING_STRING;
   outv[0].val.t = 0;
-  outv[0].sz = -1;
+  outv[0].sz = 0;
   outv[1].type = YAP_STRING_STRING;
   outv[1].val.t = th;
   if (!Yap_Splice_Text(2, NULL, &inp, NULL, outv PASS_REGS))
diff --git a/packages/real b/packages/real
index a383bfd51..5a72fe49e 160000
--- a/packages/real
+++ b/packages/real
@@ -1 +1 @@
-Subproject commit a383bfd51144172fdea8463bd56e9308742e5de2
+Subproject commit 5a72fe49e5a5c651a890a388eb967b83da8e2c52
diff --git a/pl/absf.yap b/pl/absf.yap
index b7f4809c1..3b4845a7b 100644
--- a/pl/absf.yap
+++ b/pl/absf.yap
@@ -224,7 +224,7 @@ absolute_file_name(File,Opts,TrueFileName) :-
 	(Type == directory ->
 	 exists_directory(F0)
 	;
-	 \+ exists_directory(F0) % if it has a type cannot be a directory.
+	\+ exists_directory(F0) % if it has a type cannot be a directory.
 	).
 
 '$add_extensions'([Ext|_],File,F) :-