There is no actual update option that can be used to add or extend records in a PDS. If you want to extend or add a record within a member, you must rewrite the complete member in another area of the data set. Because space is allocated when the data set is created, there is no need to request additional space. Note, however, that a PDS must be contained on one volume. If sufficient space has not been allocated, the data set must be reorganized by the IEBCOPY utility program or ISPF.

When you rewrite the member, you must provide two DCBs, one for input and one for output. Both DCB macros can refer to the same data set, that is, only one DD statement is required.