The same exit point can be used for all four exits. The value in the PEDB field PEDBEXITPOINTID identifies the exit point that is hit. For example, If PEDBEXITPOINTID is PEDB_BPX_PREPROC_INIT, the preprocess initiation exit point is hit. The constants that identify each exit point are defined at the bottom of the PEDB (see BPXYPEDB — Mapping of process exit data block).
See Using installation exits in z/OS UNIX System Services Planningfor more information about the process start/end installation exits.