Add a knob LIBPTHREAD_BIGSTACK_MAIN, which instructs libthr to leave the whole RLIMIT_STACK-sized region of the kernel-allocated stack as the stack of main thread.
Add a knob LIBPTHREAD_BIGSTACK_MAIN, which instructs libthr to leave the whole RLIMIT_STACK-sized region of the kernel-allocated stack as the stack of main thread.