For journalizing transactions (when VSAM exits because of a GET, PUT, or ERASE), you can use the SHOWCB macro to display information in the request parameter list about the record that was retrieved, stored, or deleted (FIELDS=(AREA,KEYLEN,RBA,RECLEN), for example). You can also use the TESTCB macro to find out whether a GET or a PUT was for update (OPTCD=UPD).
If your JRNAD routine only journals transactions, it should ignore reason X'0C' and return to VSAM; conversely, it should ignore reasons X'00', X'04', and X'08' if it records only RBA changes.