Although any number of segments can be added to a DMCL, z/OS places a limit on the number of files that can be accessed within a single job step. This is a runtime restriction, since the DMCL can contain the definition of any number of files; however the number that can be accessed concurrently is limited.
Normally a z/OS job step can access up to 3,273 files. CA IDMS has extended this limit for a CV, to allow up to 10,000 files to be accessed using dynamic allocation and 3,273 files to be accessed using DD statements.
Note: Since the maximum number of DD statements that can be associated with a job step is 3273, if the number of database files in a DMCL is close to or exceeds this limit, dynamic allocation should be used for all database files so that the limit will not prevent the use of DD statements to override dynamically allocated files when necessary.
Increasing the number of files beyond the 3273 limit has implications for manual recovery, since the increased limit is supported only for CVs and not local mode batch jobs such as utility executions. To perform manual recovery, it may be necessary to execute the ROLLBACK or ROLLFORWARD utility statement multiple times, recovering a subset of the areas or segments in each execution.
Note: For more information about the impact on recovery, see 21.2, “Backup Procedures".
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