Using User Exits

DFSMS provides user exit locations as part of macros and commands where you can specify the name or address of your user-written exit routine. The DCB macro, VSAM macros, and some access method services commands contain parameters in which you specify the address or name of your exit routine. Some data set utility programs also provide user exit locations for modifying data set processing.

You can create a library of proven user exits to provide standard functions for frequently used exits; however, each user program must request the exits. Application programmers can create their own exit routines instead of the ones you provide.

User exit routines do not need to be reentrant.

User exits are available at various points in data set processing, such as:

End-of-data
I/O errors
Logical errors
Non-VSAM abend conditions
Open, close, and end-of-volume processing
DESERV macro processing

For more information on the user exits available in DFSMS, see the following publications.

Document	Order Number
z/OS DFSMS Access Method Services Commands	SC23-6846
z/OS MVS Program Management: Advanced Facilities	SA23-1392
z/OS DFSMS Using Data Sets	SC23-6855
z/OS DFSMSdfp Utilities	SC23-6864
z/OS DFSMSrmm Implementation and Customization Guide	SC23-6874

The DESERV user exit is described in z/OS DFSMSdfp Advanced Services.