How do I find the maximum stack size?

Question

I am working on Ubuntu 11.04. How do I find out the maximum call stack size of a process and also the size of each frame of the stack?

Finnic

Answer 1

You can query the maximum process and stack sizes using getrlimit. Stack frames don't have a fixed size; it depends on how much local data (i.e., local variables) each frame needs.

To do this on the command-line, you can use ulimit.

If you want to read these values for a running process, I don't know of any tool that does this, but it's easy enough to query the /proc filesystem:

cat /proc/<pid>/limits

Shingly

I get a command not found error. What package do I need to install for this command? – Finnic

They need to have some starting size right? Does the compiler calculate beforehand the size of stack frame (taking into account all the local variables) and then allocate the frame? – Finnic

@Bruce: Yes, it's largely up to the compiler how stack frames are laid out and sized. "Creating" a frame is as simple as adjusting the stack pointer to leave enough room for the called function to carry out its business. Also, calls to alloca() (and maybe others) can grow the frame dynamically. – Shingly

Answer 2

A quick Google search should reveal some information on this subject.

> ulimit -a         # shows the current stack size

Acosmism

Of course, a quick google search now serves up this page. – Interrelate

...and the link is dead. Also, it's ulimit -s to show the stack size. – Malaco

Values are in kilobytes, except for -t, which is in seconds and -n and -u, which are unscaled values. -- man pages – Cosma

Answer 3

The following call to ulimit returns the maximum stack size in kibibytes (2¹⁰ = 1024 bytes):

ulimit -s

Dorsey

Answer 4

You can use getrlimit to see the stack size and setrlimit to change it.

There's an example in the Increase stack size in Linux with setrlimit post.

Enidenigma

Answer 5

getrlimit() and setrlimit() are not Linux commands. They are system calls.

So in order to get the result of them, you need something like a bash script or any other executable script that returns the result of the system call.

Dave