_CEE_HEAP_MANAGER

Specifies the name of the Vendor Heap Manager (VHM) DLL that will be used to manage the user heap. You set the environment variable as follows:
_CEE_HEAP_MANAGER=dllname
This environment variable must be set using one of the following mechanisms: Either of these mechanisms is before any user code gets control. This means prior to the HLL user exit, static constructors, and/or main getting control. Setting of this environment variable once the user code has begun execution will not activate the VHM, but the value of the environment variable will be updated.

See z/OS Language Environment Vendor Interfaces for more information on the Vendor Heap Manager support.