Extended Heap Operations APIs

The extended heap operations APIs are:

Create Heap (CEECRHP) creates a new heap.
Discard Heap (CEEDSHP) discards an existing heap.
Mark Heap (CEEMKHP) returns a token that can be used to identify heap storage to be freed by the CEERLHP API.
Release Heap (CEERLHP) frees all storage allocated in the heap since the mark was specified.