The initialization exit (ARCINEXT) can perform tasks of your choosing before returning to DFSMShsm during DFSMShsm startup time. For example, the exit can open and read a data set containing installation control records for building tables. The address of the tables can be stored in the installation-reserved fields of the MCVT control block. These tables can contain information required by other installation exits.

To find an MCVT, the exit uses the field MQCTHADR as a pointer to a linked list of elements, each of which (MQCTHOST) represents one DFSMShsm host in some address space with its own MCVT. (The last element in this list has binary zeros in its MQCTH_NEXT field.) To access the proper MCVT, subsequent installation exits need to search the chain starting at MQCTHADR for the element with MQCTH_ASCB that points to the current address space control block. MQCTH_MCVT in that element points to the proper MCVT with its user fields. Subsequent installation exits can refer to these user fields in the MCVT control block by the following method: