I recently learned about stacks, so I was experimenting to see what the stack size is and what happens when it overflows. I found out that on Unix the default stack size is 8 MiB, and that supports my findings since I cannot declare a string having size greater than or equal to 8 MiB in my main function. However, when I declare a variable in main() it affects other functions. For example:
#include <stdio.h>void foo(void){ long int size = 1024*1024*2; char str[size]; str[size - 1] = 'a'; printf("%c\n", str[size - 1]);}int main(int argc, char** argv){ long int size = 1024*1024*6; char str[size]; str[size - 1] = 'a'; printf("%c\n", str[size - 1]); foo(); return 0;}This code results in segmentation fault but if I make the string size 5 MiB in main() then there is no segmentation fault. Does that mean my C program cannot allocate more than 8 MiB of RAM for local variables (of all functions)? If so, what IS the point of stacks?