Calling Sequence

.A call sequence allocates an activation record and enters information into its field
.A return sequence restores the state of the machine so that calling procedure can continue execution

A call sequence allocates an activation record and enters information into its fields. A return sequence restores the state of the machine so that the calling sequence can continue execution. Calling sequence and activation records differ, even for the same language. The code in the calling sequence is often divided between the calling procedure and the procedure it calls. There is no exact division of runtime tasks between the caller and the callee. As shown in the figure, the register stack top points to the end of the machine status field in the activation record. This position is known to the caller, so it can be made responsible for setting up stack top before control flows to the called procedure. The code for the callee can access its temporaries and the local data using offsets from stack top.