Why is the ACCESS DF_DS_OP option not working for partitioned data areas?
On non-partitioned tables, only the index datasets are being opened as documented but for partitioned tables it is opening both the index datasets and the data area datasets.
z/OS
The ACCESS DF_DS_OP feature was introduced by PTF RO92259. It reduces 24-bit memory in the MUF region by deferring the OPEN of a data area until the first command to add or read a row. Index areas are excluded from this processing. Partitioned data areas are also excluded due to the complex validation processing involved in opening partitioned data areas.
See Use ACCESS DF_DS_OP to Defer the DATA Set of a URT OPEN section on Datacom documentation