Allowing DFSMShsm to use the 3590-1 generic unit when it contains mixed track technology drives

You may have conditions where you need to use the 3590-1 generic unit but it contains a mixture of 3590 devices that cannot share tapes. When this condition occurs, you must use other means, such as SMS ACS routines, to keep these drives separate and you can use the following patch to disable the DFSMShsm compatibility checking:

PATCH .MCVT.+3D5 BITS(.1......)

You can use the following patch to re-enable the DFSMShsm compatibility checking:

PATCH .MCVT.+3D5 BITS(.0......)

By default, the checking is done for non SMS tape allocations. When the checking is enabled, non SMS tape allocations for generic unit 3590-1 containing mixed track technologies cause ARC0030I to be issued. The allocation is allowed to proceed when the message is issued, but results in an OPEN failure if a tape/tape unit mismatch occurs. ARC0030I is not issued for a mix of tape units sharing a common write format, for example 3592-2 with 3592-3E.