Providing ENQ resource information on DISPLAY GRS command

The ENQ API issuer provides a qname, rname, and scope to identify the resource to serialize; this all that the DISPLAY GRS command can use to present information about the resource. In many cases, it is hard for the operator or systems programmer to understand what these values represent. As such, global resource serialization provides the ISGDGRSRES installation exit to allow the application to add additional information for a given resource on the DISPLAY GRS output. See the 'ISGDGRSRES - Display global resource serialization resource exit' in z/OS MVS Installation Exits for more details on how to use the exit.

Note: The additional description information which is gotten by calling the exit may be used in other cases beyond the display GRS command where the information can provide additional diagnostic information.

z/OS® Automatic Tape Switching (ATS STAR) provides a good example of the ISGDGRSRES exit's use. ATS STAR obtains an ENQ to serialize access to a tape device. Next, the ENQ uses the ATS STAR QNAME of SYSZATS and an RNAME equal to the device's unique node element descriptor (NED). A NED is not in a human readable format, so ATS STAR uses the ISGDGRSRES exit to add the device type and number to the DISPLAY GRS command output.

In the following DISPLAY output, the field: "ADDITIONAL RESOURCE INFORMATION FROM:" was added as a result of ATS STAR's ISGDGRSRES exit translating the RNAME NED into a readable format.

ISG343I 09.13.24 GRS STATUS 539
S=SYSTEMS SYSZATS  NED 003490B40VSSGA05B8000002A9
SYSNAME   JOBNAME         ASID     TCBADDR   EXC/SHR      STATUS
SY1       ALLOC4          0027     006FF448  EXCLUSIVE    OWN
ADDITIONAL RESOURCE INFORMATION FROM:  ALLOCAS IEFAIRSX
349S AT UNIT ADDRESS 05B8 (AUTOSWITCH)