Stack Allocation

Figure shows the activation records that are pushed onto and popped for the run time stack as the control flows through the given activation tree. First the procedure is activated. Procedure readarray 's activation is pushed onto the stack, when the control reaches the first line in the procedure sort . After the control returns from the activation of the readarray , its activation is popped. In the activation of sort , the control then reaches a call of qsort with actuals 1 and 9 and an activation of qsort is pushed onto the top of the stack. In the last stage the activations for partition (1,3) and qsort (1,0) have begun and ended during the life time of qsort (1,3), so their activation records have come and gone from the stack, leaving the activation record for qsort (1,3) on top.