Index: /trunk/source/lisp-kernel/x86-exceptions.c
===================================================================
--- /trunk/source/lisp-kernel/x86-exceptions.c	(revision 15470)
+++ /trunk/source/lisp-kernel/x86-exceptions.c	(revision 15471)
@@ -2320,6 +2320,9 @@
 {
   stack_t stack;
+
+  stack.ss_size = SIGSTKSZ*8;
+  stack.ss_flags = 0;
 #ifdef SEPARATE_ALTSTACK
-  stack.ss_sp = mmap(NULL,SIGSTKSZ*8, PROT_READ|PROT_WRITE|PROT_EXEC,MAP_ANON|MAP_PRIVATE,-1,0);
+  stack.ss_sp = mmap(NULL,stack.ss_size, PROT_READ|PROT_WRITE|PROT_EXEC,MAP_ANON|MAP_PRIVATE,-1,0);
 #else
   stack.ss_sp = a->low;
@@ -2327,6 +2330,4 @@
   mmap(stack.ss_sp,stack.ss_size, PROT_READ|PROT_WRITE|PROT_EXEC,MAP_FIXED|MAP_ANON|MAP_PRIVATE,-1,0);
 #endif
-  stack.ss_size = SIGSTKSZ*8;
-  stack.ss_flags = 0;
 #ifdef LINUX
   /* The ucontext pushed on the altstack may not contain the (largish)