// First we will push a 0 integer onto the stack
// If you require a pointer to an int, then push your int value instead.
push 0

// esp is the pointer to the stack which is the top value (latest push)
// the stack is is 4 byte aligned (int or dword size)
myFunction(esp);

// finished with the int, remove it from the stack without trashing a register
add esp, 4

inline function filewrite(handle, text, len) {
      push eax
      WriteFile($handle,$text,$len,esp,0);
      add esp, 4
      
      $return eax;
}

 sub Esp,4
or
 Esp -= 4;

sub Esp, 16 // 16 bytes variable