A JRNAD exit routine can be provided to record transactions against a data set, to keep track of changes in the RBAs of records, and to monitor control interval splits. It is only available for VSAM shared resource buffering. When using the JRNAD exit routine with compressed data sets, all RBAs and data length values returned represent compressed data. For shared resources, you can use a JRNAD exit routine to deny a request for a control interval split. VSAM takes the JRNAD exit each time one of the following occurs:

• The processing program issues a GET, PUT, or ERASE
• Data is shifted right or left in a control interval or is moved to another control interval to accommodate a records being deleted, inserted, shortened, or lengthened
• An I/O error occurs
• An I/O completion occurs
• A shared or nonshared request is received
• The buffer contents are to be changed.