When using the GCFS, GCFE, GNFS or GNFE function calls, the ()-CAT-FILE-STATUS-FIELDS is populated.
If a catalog file access error occurs during a call to the file, the MVSCATPB return code, ()-RETCODE, is populated with a value of 20, and the reason code, ()-RSNCODE, is populated with a value of 78-cat-file-access-error (46).
The ()-pc-dsn field contains the catalog file that gave the error, not the pc-dsn of the catalogued dataset record.
When the requested catalog number, ()-CAT-FILE-NUM, is greater than the number of catalogs, ()-NUM-CATS, reason code 78-invalid-cat-file-number is returned from the catalog file status calls.