Could be one of the following reasons:
->Conflicting or incomplete parameters in DCB, such as BLKSIZE not a multiple of LRECL, or
missing SYSIN DD;
->Tried to create a PDS without allocating directory blocks;
->Member name specified in DD not found;
->no directory allocation sub parameter in DD;
->Open output dataset as input;
->Track overflow or updating attempted, but not supported by the OS.
->May be a record length or OPEN statement error.