diff --git a/rtl/atari/system.pas b/rtl/atari/system.pas
index 0ea4586854..70e369390f 100644
--- a/rtl/atari/system.pas
+++ b/rtl/atari/system.pas
@@ -747,8 +747,13 @@ end;
                          SystemUnit Initialization
 *****************************************************************************}
 
+function CheckInitialStkLen (StkLen: SizeUInt): SizeUInt;
+begin
+  CheckInitialStkLen := StkLen;
+end;
 
 begin
+  StackLength := CheckInitialStkLen (InitialStkLen);
 { Initialize ExitProc }
   ExitProc:=Nil;
 { Setup heap }
diff --git a/rtl/beos/system.pp b/rtl/beos/system.pp
index 4b12f72c66..e984f3346c 100644
--- a/rtl/beos/system.pp
+++ b/rtl/beos/system.pp
@@ -531,6 +531,7 @@ begin
   myheaprealsize:=$2000;
   myheapstart:=nil;
   heap_handle:=sys_create_area('fpcheap',myheapstart,0,myheaprealsize,0,3);//!!
+  StackLength := CheckInitialStkLen (InitialStkLen);
   if heap_handle>0 then begin
     InitHeap;
   end else system_exit;
diff --git a/rtl/emx/system.pas b/rtl/emx/system.pas
index 327287f3c1..b7b5118d39 100644
--- a/rtl/emx/system.pas
+++ b/rtl/emx/system.pas
@@ -445,6 +445,11 @@ begin
                                                  else GetFileHandleCount := L2;
 end;
 
+function CheckInitialStkLen (StkLen: SizeUInt): SizeUInt;
+begin
+  CheckInitialStkLen := StkLen;
+end;
+
 var TIB: PThreadInfoBlock;
     PIB: PProcessInfoBlock;
 
@@ -558,6 +563,7 @@ begin
             end;
     end;
     exitproc:=nil;
+    StackLength := CheckInitialStkLen (InitialStkLen);
 
     {Initialize the heap.}
     initheap;
diff --git a/rtl/os2/system.pas b/rtl/os2/system.pas
index 1969a8626e..5d97325d84 100644
--- a/rtl/os2/system.pas
+++ b/rtl/os2/system.pas
@@ -694,6 +694,11 @@ begin
                                                  else GetFileHandleCount := L2;
 end;
 
+function CheckInitialStkLen (StkLen: SizeUInt): SizeUInt;
+begin
+  CheckInitialStkLen := StkLen;
+end;
+
 var TIB: PThreadInfoBlock;
     RC: cardinal;
     ErrStr: string;
@@ -707,6 +712,7 @@ begin
     DosGetInfoBlocks (@TIB, @PIB);
     StackBottom := TIB^.Stack;
     StackTop := PtrUInt (TIB^.StackLimit);
+    StackLength := CheckInitialStkLen (InitialStkLen);
 
     {Set type of application}
     ApplicationType := PIB^.ProcType;
diff --git a/rtl/palmos/system.pp b/rtl/palmos/system.pp
index bccdf46e89..e4a31a71f9 100644
--- a/rtl/palmos/system.pp
+++ b/rtl/palmos/system.pp
@@ -110,5 +110,6 @@ begin
 end;
 
 begin
+   StackLength := CheckInitialStkLen (InitialStkLen);
    ExitCode:=0;
 end.