USERUNITTABLE and NOUSERUNITTABLE: Specifying esoteric tape unit names to DFSMShsm

The SETSYS USERUNITTABLE command has two functions:

to identify esoteric tape unit names to DFSMShsm.
to control translation of esoteric output unit names.

The SETSYS USERUNITTABLE command must always be coded for esoteric unit names used by DFSMShsm whether translation is required or not. All esoterics identified to DFSMShsm with the SETSYS USERUNITTABLE command must appear in a single command.

To identify esoteric tape unit names to DFSMShsm, you must first define these esoteric tape unit names to MVS™ during system I/O generation. Then, you must include the esoteric tape unit names in a DFSMShsm SETSYS USERUNITTABLE command. Only after they have been successfully specified with the SETSYS USERUNITTABLE command can they be recognized and used as valid unit names with subsequent DFSMShsm commands.

For the DFSMShsm commands required to restrict device selection, see topic about implementing DFSMShsm tape environments in z/OS DFSMShsm Implementation and Customization Guide, specifically:

For SMS-managed tape libraries, see the topic about information that is passed to an ACS routine.
For other tape libraries (such as non-SMS or nonlibrary), see the topic about restricting device selection.

To control the translation of output unit names, you can use the SETSYS USERUNITTABLE specifications of output unit names to input unit names. Translation occurs for translation-eligible esoteric groups. These include:

3480 device types with all online units of the esoteric group having cartridge loaders
3490 device types
3590 device types

Translation occurs during output processing so that when the tape units are used for input, the translated unit name is used for allocation.

There are three forms of specifications you can use to identify esoteric tape unit names to DFSMShsm:

first, translation is not specified (es1)
second, translation is specified to a different unit name (es2out:es2in)
third, translation is specified to the same unit name (es3:es3)

Explanation: When you specify USERUNITTABLE(es1, es2out:es2in, es3:es3), you are identifying four separate esoteric tape unit names in three independent specifications. You can use any of these forms of specification to identify esoteric tape unit names to DFSMShsm. You can combine specifications as we have shown here, but remember that all esoterics used in another DFSMShsm command must appear in a single SETSYS USERUNITTABLE command. Each separate form of specification is explained below.

When you specify a single esoteric (es1), the esoteric tape unit name es1 is identified to DFSMShsm as valid. Output allocations are made to units associated with the particular esoteric tape unit name requested for the output function. Any cartridge loader esoteric translation is assigned to the generic unit name equivalent to the type of units associated with the esoteric tape unit name. Substitute your esoteric name for es1.

When you specify an out-and-in esoteric pair (es2out:es2in), the esoteric unit names es2out and es2in are identified to DFSMShsm as valid. Translation to an esoteric can take place. The esoteric unit name requested for the output allocation (es2out) may be translated to the esoteric tape unit name specified to the right of the colon (es2in) when output processing is completed. If translation occurs, then when the tape volume is requested to be read, input allocations are made to units associated with es2in. The purpose of this translation is to allow the user to use different devices for input than output. Substitute your esoteric names for es2out and es2in.

When you specify (es3:es3), the esoteric unit name es3 is identified to DFSMShsm as valid. Since the same esoteric unit name is specified for both input and output, the same units are candidates for input allocations and output allocations. Substitute your esoteric name for es3.

The following discussion presents two examples. One is very general and one is specific. Please note that any values specified here are only examples and should not be interpreted as the values to be used for your system.