Macro overview

The following JES2 control service programs provide a comprehensive set of services that aid the JES2 processors in performing their respective tasks in an efficient manner without burdening the programmer with needless detail. These services are requested by the processor with JES2 macro instructions. The macros should not be used in code executing outside the control of the JES2 dispatcher unless stated in the description of the individual macro instruction.

General storage management: Provide for the acquisition and release of JES2 buffers
Work area management services: Provide for the acquisition and return of work areas that are chained off the processor control element (PCE)
Virtual page service macros: Provide for the acquisition and release of virtual pages
Job queue services: Provide for the alteration of job queues
Direct-access space services: Provide for the allocation and deallocation of JES2 direct-access storage space
Unit services: Provide for the acquisition and release of JES2 input/output units
Input/output services: Provide communication with operating system input/output supervisor
Console services: Provide all communication with the operator and manipulate associated buffer resources
Time services: Provide for the setting and interrogation of the interval timer
Synchronization services: Provide synchronization and communication between JES2 processors, the JES2 dispatcher, and the operating system
System management facilities services: Provide the processors with an interface to the MVS™ SMF routines
Installation exit services: Provide the $EXIT macro that is used to define exit points in JES2
Debug services: Provide facilities for aid in debugging JES2
Error services: Provide a uniform way of processing detected errors
Recovery processing aids: Provide macros to aid in recovery processing
Coding aid services: Provide the JES2 programmer with coding aids not usually available in the operating system, but useful in coding JES2 routines
Print/punch output services: Provide macros used to define separator pages and create peripheral data information records
Job control table extension services: Provide macros used to add, expand, locate, and remove extensions to the job control table ($JCT). Installations can use these extensions to store and transmit job-related information from node to node.
Job output services: Provide macros used for job output services
Initialization services: Provide macros to generate initialization statement (and parameter) tables and checkpoint information tables
Verify services: Provide facilities to build control block verification tables to verify spool-resident control blocks
Table services: Provide facilities for scanning JES2 initialization statements, dynamically creating control blocks for DCTs, PCEs, and DTEs.
Miscellaneous services: Provide miscellaneous services such as modify the current JESNEWS data set and switch addressing mode

Some of the above services are provided by inline code expansion wherever the macro instruction is used. The remaining services are provided by routines that are integral parts of the control service programs. At execution time, the macro expansion passes information to the control program routine to specify the exact nature of the service to be performed. This information is broken down into parameters and, usually, is passed to the routine through general purpose registers called parameter registers.