CA 1 normally does not allow double opens or recreates. If the DB2UTILB program attempts a double open or recreate, the job will ABEND with an IEFTMS50 7XX-04 and an IECTMS3 NS(64) message.
To avoid this you can code the TMSXITF exit and allow DB2UTILB to perform double opens or recreates. A skeleton of the exit can be found in the CTAPSAMP library and a USERMOD for it can be found in the CTAPJCL library under the same name. You will need to add code at both the volume and DSNB check for double opens and recreates.
In the exit you have access to the VOLUME or DSNB records from the TMC. You can use any field in these records, such as DSN, CJOB, and CPGM, to help decide if the double open or recreate should be allowed. See the Programmers Guide for more information on the exit and the fields in VOLUME and DSNB records.