Partitioned data sets (PDS) and partitioned data sets extended (PDSE) can be used as directories, and their members are files within those directories. An illustration of the use of PDSs to act as directories is shown in Figure 1. For general information on PDSs and PDSEs, see z/OS DFSMS Using Data Sets.

You cannot create new directories within a PDS or PDSE, due to the nature of these data structures. Updates or appends to a member name are not allowed.

The partitioned data set can only allocate on a single volume with the maximum size of 65535 tracks. See z/OS DFSMS Using Data Sets for additional information on MVS file size limits.