Data set availability

The scheduler determines the availability of a data set by using information from the previous job runs. In some cases, the scheduler is not able to determine availability where there have been no actions against the data set in the previous runs. Thus, the scheduler establishes availability as follows:
  • The data set is available and cataloged if there are no JCL statements that allocate it in the job.
  • The data set is not available if there are JCL statements that allocate it in the job.

For example, a step refers to an existing data set with the disposition SHR. This step has never run, thus the data set is available.