Overrides

If you code SYSOUT and UNIT on the same statement, the SYSOUT parameter overrides the UNIT parameter.

The system also obtains device information when the system obtains volume serial information from:

A VOLUME=REF=dsname reference to an earlier data set.
A VOLUME=REF=ddname reference to an earlier DD statement.
The volume(s) for a passed data set.
The catalog for a cataloged data set.

However, you can override the retrieved device information if the device you specify is a subset of the retrieved device information; otherwise the system ignores the overriding device information. For example, if the retrieved unit grouping is 3390, and the specified unit subparameter is 3390A (a subset of 3390), then the system allocates from the devices contained in 3390A.

If you have 3490 Magnetic Tape Subsystem models A10 and A20 defined to your system and you use one of the IBM-generated group names SYS3480R or SYS348XR, the system overrides the device type retrieved from the catalog with a device from the esoteric device group.

For more about how the system uses device information it retrieves from the catalog, see the text about the relationship of the UNIT and VOLUME parameters for non-SMS-managed data sets in z/OS MVS JCL User's Guide.

Note: LABEL=(n,,,IN) is the system-managed tape library equivalent of either UNIT=SYS3480R or UNIT=SYS348XR.

You can mount 3480-formatted or 3480X-formatted (18-track formatted) tape volumes, that are not extended, on a 3490 tape device (36-track write, 18-track or 36-track read).