One way to allow multiple operating systems to access a common data structure would be to place the data structure on a DASD device that has been genned with the “shared” attribute. Programs accessing that data structure could serialize access to the data structure by using the IBM RESERVE/DEQ macros. Serialized access is achieved with hardware reserves if the device is genned properly on all systems, and the macros are coded properly in all programs accessing the data structure. DASD controller hardware reserve microcode ensures that only a single program on a single system is able to read and update the data structure at any given moment.
The CA MIM DASD Reserve Validation Utility allows sites to determine whether the hardware reserve process is working properly for a particular shared DASD device. If a reserve failure is detected, then an error message is issued and the utility abends with a U0011 .
Note: The MIMPROOF program issues hardware reserves with a QNAME of MIMPROOF. This QNAME should not be specified in the MIMQNAME member if the SELECT is specified on GDIINIT PROCESS. If ALLSYSTEMS is specified on GDIINIT PROCESS, then the MIMQNAME member should be updated with the following entry: MIMPROOF GDIF=NO
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