Unbreak non-x86 and in particular ia64, The default stack size
on ia64 is 32KB. Unconditionally hardcoding a 16KB stack for
reasons of increasing the stack size on i386 is just wrong. If
the size was indeed expressed in terms of pages, as the commit
log suggested, then it would happen to be just right for ia64,
though only accidentally.

Pointy hat: avg, pjd