Opening an input data set

If you specify or default to IBM standard labels, the first record on the input tape must be an IBM standard volume label (VOL1). At the time the data set is opened, the system checks the first record on the tape to determine whether the record is 80 bytes long and contains the identifier VOL1 in the first 4 bytes. The various error conditions that can occur during verification of the first record are explained in IBM standard volume label editor routines.

Before OPEN verifies the volume, OPEN will abnormally terminate if the system-wide RACF tape protection option is specified and the DD statement specifies PROTECT=YES without previously opening the DD statement for output processing.