Abstract for MVS Installation Exits

This information supports z/OS® (5694-A01). This information identifies and describes the installation exits that you can use to modify your MVS™ system.

Who should use this information:

This information is intended for a systems programmer who wants to modify the processing of an MVS system. The information assumes that the reader can code in assembler language and read assembler, loader, and linkage editor output.

Although the documentation for the exits in this information follows a standard format, each exit has unique features and requirements that you need to know about. In general, the introductory to each exit describes the exit's functions and the possible uses for the exit. Other topics point out specific considerations for coding the exit.

How to use this information:

Because all of the exits perform the general function of modifying the existing code, you may find it helpful to read the topic All About Exit Routines to develop a general idea of what an exit is and how it functions as a part of the MVS system.

Once you have determined the type of modification you want to make to your system, you might follow these general steps when using the information:
  • Use the table of contents to locate the exit that might fit your needs.
  • Turn to the description of the exit and use the corresponding introductory topic that provides a description of the exit routine and its possible uses, to determine if the exit routine can meet your needs.
  • Use the detailed information to design, code, and install your installation exit routine.

How each exit is organized:

The exit routines in this information follow a format to allow you to locate information about the exit routine you are coding. The list that follows describes how each exit can be organized. However, some of these topics may not apply to every exit, such as I/O restrictions. A topic that does not apply to the exit is not discussed for that exit.
  • Exit routine name and description.
  • Introductory material, which describes the function of the exit routine and lists possible uses for the routine.
  • Installing the exit.
  • Exit routine environment, which contains specific environmental considerations that you need to know, such as the address space that the exit runs in, the AMODE and RMODE for the exit, and locks or ENQs that the exit routine might hold when it gets control.
  • Exit recovery environment, which describes the type of recovery environment for the exit routine.
  • Processing.
  • Programming considerations.
  • Macro instructions and restrictions, which contain specific macro requirements or restrictions that you must keep in mind when coding the exit routine.
  • I/O restrictions.
  • Entry specifications, which includes a list of the register contents when the exit routine receives control and, when applicable, describes any related parameter lists for the exit routine.
  • Return specifications, which lists the register contents expected when the exit routine returns control to the calling program.
  • Coded example of the exit.