Maximum Stack Size for C/C+ Program?

问题:

I've tried the below program. The intent by which this program was created is to discover more about stack sizes.

int main()
{
    int nStack[100000000];
    return 0;
}

After executing the above code, the program crashes due to huge stack size allocation. What is the maximum possible size of the stack? Is it fixed for every program/computer? Can it be increased?

I want to know for the sake of knowledge. If anyone can provide examples in C/C++, it would be very helpful.

回答1:

What is the maximum size of the stack?

Depends on implementation. One to few megabytes is typical on PC nowadays.

Is it fixed for every program/computer?

It's typically fixed on linking but standard does not define that it is. Some operating systems can limit the stack during runtime too (RLIMIT_STACK on linux for example).

Can it be increased?

It may be possible depending on implementation. See the documentation of your linker for details. And possibly the documentation for the OS and the executable format too.

You should allocate huge arrays like that dynamically.

回答2:

For Linux based applications, we can use getrlimit and setrlimit API's to know various kernel resource limits, like size of core file, cpu time, stack size, nice values, max. no. of processes etc. 'RLIMIT_STACK' is the resource name for stack defined in linux kernel. Below is simple program to retrieve stack size :

#include <iostream>
#include <sys/time.h>
#include <sys/resource.h>
#include <errno.h>
using namespace std;

int main()
{
   struct rlimit sl;
   int returnVal = getrlimit(RLIMIT_STACK, &sl);
   if (returnVal == -1)
   {
      cout << "Error. errno: " << errno << endl;
   }
   else if (returnVal == 0)
   {
      cout << "stackLimit soft - max : " << sl.rlim_cur << " - " << sl.rlim_max << endl;
   }
}

回答3:

To change the size of the stack allocated for the main thread that is raised by the process loader to run the code at it's entry point, look to your linker documentation. It's also possible to edit that stack size in the executable header metadata.

回答4:

I tried below program.

int main()
{
    int nStack[519492];
    cout<<"Okay!";
    return 0;
}

The output:

Okay!

But if I increase the array size by 1 byte, the program crashes.

int main()
{
    int nStack[519493];
    cout<<"Okay!";
    return 0;
}

Output:

No output. Program crashes.