Stack overflow in Fortran 90

Question

I have written a fairly large program in Fortran 90. It has been working beautifully for quite a while, but today I tried to step it up a notch and increase the problem size

Answer 1

Not all of the memory is created when the program starts. When you call the subroutine the executable is creating the memory that the subroutine needs for local variables. Typically arrays with simple declarations that are local to that subroutine -- neither allocatable, nor pointer -- are allocated on the stack. You could have simply run of of stack space when you reached these declarations. You might have reached a 2GB limit on a 32-bit OS with some array. Sometimes executable statements implicitly create a temporary array on the stack.

Possible solutions: 1) make your arrays smaller (not attractive), 2) make the stack larger), 3) some compilers have options to switch from placing arrays on the stack to dynamically allocating them, similar to the method used for "allocate", 4) identify large arrays and make them allocatable.