This exit is taken in the initialization routine that processes the initialization options (IROPTS, in module HASPIRMA). The initialization options are taken from the parameter field specified through the JES2 procedure or START command, or are requested from the operator through the $HASP426 WTOR message if necessary. The point of processing for this exit is just before parsing and analyzing the options and setting appropriate flags. Exit 0 may be called a multiple number of times, because new options may be requested repetitively through the $HASP427 WTOR message until valid options are specified or the exit directs JES2 to bypass the options analysis.

The exit control blocks and the exit effector are not initialized at this point in IROPTS when Exit 0 gets control. Therefore, the normal JES2 exit facility initialization parameters cannot be used. IROPTS searches for module HASPXIT0 in the HASPINIT load module and then, if necessary, in the HASJES20 load module. The name HASPXIT0 is defined as a weak external reference (WXTRN) in both load modules. If HASPXIT0 is not found through this search, JES2 attempts to locate a separate load module named HASPXIT0. Creating separate load modules for your exit routines is recommended. If HASPXIT0 is found in STEPLIB or LINKLIST, a temporary XIT and XRT are built for the exit facility and the $EXIT macro. The HASPXIT0 module's MIT is searched for all entry point names of the form 'EXIT0nnn' and the entry point names found and the associated addresses are placed in the temporary XRT in the order they are found.

If HASPXIT0 is found during JES2 initialization, an entry for that module is placed in the exit facility LMT as if a LOADmod(jxxxxxxx) initialization statement had been processed for it and the module is not deleted. Therefore other exit routines (e.g., for Exits 19 and 24) and installation-defined tables (e.g., initialization statement $SCANTAB tables) can be assembled in the same module with the Exit 0 routines without having them deleted by JES2 after initialization completes. Note, however, that HASPXIT0 will be deleted from storage with HASPINIT if HASPXIT0 is linkedited with the HASPINIT load module. Exit 0 can also be invoked using the MVS™ Dynamic exit facility. JES2 invokes exit HASP.$EXIT0 immediately after the call to routines in HASPXIT0. The interface to any routines called in this fashion is identical to those invoked from HASPXIT0.