Using PDSEs

Some of the advantages to using PDSEs are as follows:

PDSEs support member-level DDM attributes, whereas member-level attributes do not exist for PDSs.
PDSE members can contain stream files, whereas PDS members cannot. However, you can use stream access to PDS members that contain record files.
PDSEs use dynamic space allocation and reclamation, whereas PDSs need to be compressed periodically with the IEBCOPY utility.
PDSEs are always SMS-managed. PDSs are not necessarily SMS-managed.