OPEN EXTEND or OUTINX

If the data set opens with the OUTINX or EXTEND options, and its DD disposition parameter was

DISP=NEW: there are no restrictions, because the data set reallocates prior to the restart.

DISP=OLD or DISP=SHR: the data set repositions after the last record added before the job terminated. It is possible to add records twice to the data set.

DISP=MOD: the following restrictions apply to a multivolume data set:

If the volume sequence does not point to the last volume, records overlay or an abend occurs.
If the volume sequence is not supplied, loading starts on the last volume on which the data set exists. For TAPE data sets only, if the end of data occurs on a volume other than the last allocated volume, processing starts on the wrong volume.