In APAR OA42221, GRS provides monitoring of global generic queue scans using SMF type 87 records. GQSCAN and ISGQUERY REQINFO=QSCAN services can cause spikes in GRS CPU usage and GRS private storage when invoked many times for global, generic queue scans. For GQSCAN, a scan is global and generic if SCOPE=SYSTEMS or ALL, XSYS=YES or is not specified, and either the QNAME or RNAME (or both) are not specific. For ISGQUERY, a scan is global and generic if SCOPE=SYSTEMS or ANY, GATHERFROM=SYSPLEX, and either the QNAME or RNAME (or both) are not specific.

In GRS Star mode, the potential impact is greater than in other modes. SMF 87 records can help identify programs that issue global generic queue scans.

The SMF 87 records are mapped by macro ISGYSMFR. In order to access the record programmatically, use macro IFASMFR. The records contain some information about the caller. For example, the TCB, ASID, PSW, and some details about the queue scan service invocation.

To turn GRS monitoring on, specify MONITOR(YES) in your GRSCNFxx PARMLIB member, or issue the SETGRS MONITOR=YES command. You can dynamically turn the monitor on and off.

Issue DISPLAY GRS to view the MONITOR status (YES or NO) on your system.

GRS might not write the records in some cases. For example, if the caller is holding a local lock, or if there is an unexpected error with the queue scan processing.