Static vs. Dynamic Memory Allocation & Stack vs. Heap

example

int x;                 /* static storage */  void main() {    int y;              /* dynamic stack storage */    char *str;          /* dynamic stack storage */       str = malloc(100);  /* allocates 100 bytes of dynamic heap storage */     y = foo(23);    free(str);          /* deallocates 100 bytes of dynamic heap storage */ }                      /* y and str deallocated as stack frame is popped */  int foo(int z) {       /* z is dynamic stack storage */    char ch[100];     /* ch is dynamic stack storage */     if (z == 23) foo(7);        return 3;           /* z and ch are deallocated as stack frame is popped,                           3 put on top of stack  */ }