Checking available stack size in C

size_t top_of_stack;

void Main()
{
  int x=0;
  top_of_stack = (size_t) &x;

  do_something_very_recursive(....)
}

size_t SizeOfStack()
{
  int x=0;
  return top_of_stack - (size_t) &x;
}

man getrusage

int main (void)
{
  struct rlimit limit;

  getrlimit (RLIMIT_STACK, &limit);
  printf ("nStack Limit = %ld and %ld maxn", limit.rlim_cur, limit.rlim_max);
}