How can you find out the maximum size of the memory stack for a C++ program on linux? (gnu compiler)

StackOverflow https://stackoverflow.com/questions/682444

  •  22-08-2019
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Question

I am curious about how to find out what the maximum stack size is for a particular compiler/os combo. I am using Ubuntu/GNU compiler. A few questions I have in addition are:

  1. Who controls the default maximum stack size; OS or compiler?
  2. Is the default maximum scaled according to total memory? (ie a machine with 2gb memory would have larger default size than a machine with only 512mb) For this example both machines are same os/compiler setup, just different amounts of system RAM.

Thanks!

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Solution

Who controls the default maximum stack size; OS or compiler?

The compiler typically. The OS/hardware does limit it to a certain extent. Default is 8MB on linux IIRC. Think of ulimit -s on Linux (to change stack sizes).

Is the default maximum scaled according to total memory? (ie a machine with 2gb memory would have larger default size than a machine with only 512mb) For this example both machines are same os/compiler setup, just different amounts of system RAM.

No. Until and unless you do it yiurself.You can alter stack sizes via compiler switches.

ld --stack=<STACK_SIZE>

or 

gcc -Wl,--stack=<STACK_SIZE>

The C++ Standard's take on the issue of stacks and heaps:

The standard is based on an abstract machine and does not really concern itself with hardware or stacks or heaps. It does talk about an allocated store and a free store. The free store is where you'd be if you are calling new (mostly). FWIW, an implementation can have only one memory area masquerading as both stack and heap when it comes to object allocation.

Your question, therefor, boils down to be an implementation specific issue rather than a language issue.

Hope this helps.

OTHER TIPS

On Linux (Ubuntu), operating system controls the maximum size. See "man limit" or "man ulimit" for reference.

Nowadays, the correct question is: How much memory is allocated to my thread. Each thread gets an amount which typically you can control at thread-creation time.

To answer part 1, the compiler / thread-system gets to pick, although some OS's have (historically) had limits.

For 2, no it's not scaled.

There is no way of doing this portably - the C++ Standard does not actually require a stack.

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