Linux kernel/userland resizing the stack? Why only 135k initially?

Asked Oct 21 '13 at 18:10

Active Oct 21 '13 at 18:19

Viewed 89 times

I notice that when I run a minimal native Linux x86-64 application it has a stack setup for it by the kernel. When I look in /proc/<pid>/maps I see:

7ffffffde000-7ffffffff000 rwxp 00000000 00:00 0   [stack]

And when I inspect the RSP register it holds 0x7fffffffe0c0.

What I don't understand is why the stack is only 135k bytes. I would have expected the stack mmap to be in the order of megabytes on x86-64. Or does the stack mmap have some magical properties that I am not aware of?

Is it the userland applications responsibility to manually resize the stack somehow at run-time to avoid a stack overflow? If so, by what mechanism? Or does the kernel do this automatically?

edited Oct 21 '13 at 18:19

Mat

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asked Oct 21 '13 at 18:10

Andrew Tomazos

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Does this help:- http://stackoverflow.com/questions/6270945/linux-stack-sizes ? – Rahul Tripathi Oct 21 '13 at 18:12
I guess that what you need is `ulimit -s` – perror Oct 21 '13 at 18:12
@RahulTripathi: I think that is talking about stacks in kernel threads. This asks about the userland stack. – Andrew Tomazos Oct 21 '13 at 18:12
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http://unix.stackexchange.com/questions/63742/what-is-automatic-stack-expansion has some interesting info too – Mat Oct 21 '13 at 18:18
Yes, "automatic stack expansion" is what I want to know about. – Andrew Tomazos Oct 21 '13 at 18:21

Linux kernel/userland resizing the stack? Why only 135k initially?

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