JES2 IBM-defined exits

JES2 exits provide a clean, convenient, relatively stable interface between JES2 and your installation-written code. Installation-written exit routines are invoked from standard JES2 processing at various strategic locations in JES2 source code. These strategic locations in JES2 source code are called exit points. A JES2 exit is established by one or more exit points.

JES2 supports up to 256 exits; IBM® provides some exits to allow customization of the most commonly modified functions. In addition, IBM often provides new exits as new function is added to the product. These new exits provide a facility for you to alter the new processing as appropriate to meet your needs.

JES2 exits allow a wide range of customization. For example, you can add your own code to achieve the following goals:

Design your own print job separator page
Verify or change jobs submitted by TSO/E users
Change or disallow selected commands
Define alternate processing for a job that uses too many resources
Provide increased security and password checking for remote terminals and system data sets.

Using IBM-defined exits only requires that you write exit routines and incorporate the exits by using two initialization statements. IBM provides these JES2 exit points in the code. To ensure a proper implementation, however, you must thoroughly understand the IBM-defined exit and its JES2 operating environment. A comprehensive description of each exit is presented in z/OS JES2 Installation Exits.

If you find that none of these exits meet your installation's needs, you can establish your own exit point and provide your own exit routine. This requires a more thorough knowledge of JES2 processing than using an IBM-defined exit point does. However, the use of exits is still far superior to adding in-line source code modification that may require the addition of many lines of code–code that cannot be dynamically disabled in the way that an exit can.