Hi,

The getrlimit(2) page says the RLIMIT_STACK applies to "the process stack".
However, in a multithreaded app, each thread has a stack. And RLIMIT_STACK
determines the size of the thread's stack (unless overridden by the
program).

I verified this through a test program on Linux/i386 and Linux/x86_64.

The code which implements this is in
  - glibc/nptl/nptl-init.c for Linux,
  - glibc/htl/pt-create.c for the Hurd.

Patch attached.