MVS JCL requirements when using shared data tables

Before using shared data tables, you might need to change some of your JCL statements, modify your operational procedures, or increase the value of the MAXUSER MVS™ initialization parameter. This is because MVS does not allow more than one step of a job to act as a shared data table server. If a second job step attempts to act as a shared data table server, CICS® issues message DFHFC0405. Also, as job steps following the server step would also be unable to use cross-memory services with MRO, it is recommended that none of the job steps following the server step are another execution of CICS.

If a job that includes a shared data tables server step ends before all requester job steps that connected to this server have ended, the server address space is terminated by MVS. If the SDT server is running under the control of a batch initiator rather than as a started task, a new initiator must be started when this situation occurs.

MVS terminates the batch initiator with the message IEF355A INITIATOR TERMINATED, RESTART INITIATOR because for integrity reasons MVS would otherwise have to restrict the functions that could be used by the next job that runs under that initiator, which might cause the job to fail. MVS does not allow an SDT server’s ASID to be re-used until after all requester job steps that connected to the server have ended.

Related concepts
Operations with data tables
Opening a data table
Closing a data table
Interpreting data table statistics
Activating user exits for data tables
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