Question

3. Show the stack with all activation record instances, including static and dynamic chains, when execution reaches position 1 in the following skeletal program. Assume Bigsub is at level 1 procedure Bigsub is procedure A (Flag procedure Bis Boolean) is A (false) end; -of B begin -- of A if flag then B; else C; end; -of A procedureCis procedure D is end; -of D end; -- of dC begin of Bigsub A(true); of Bigsub end; -- The calling sequence for this program for execution to reach D is Bigsub calls A A callsB B calls A A callsQ C calls D

Answer 1

Stack with the activation record instances :

dynamic link static link return ( to C) dvnamic link static l return ( to A) parameter (flag) dynamic link static link return ( to B) dvnamic link static link return ( to A) parameter (flag) dynamic link static link return ( BIGSUB) dvnamic link static link return ( to caller) ari for D ari for C ari for A ari for B ari for A ari for BIGSUB stack ari: Activation Record Instances

• The chain of static links is called as static chain if it connects certain activation record instances (ari) in the stack.
• The chain of dynamic links is called as dynamic chain if connected in the stack at a given time.