Specifying the DIAGxx members

The following methods can be used to specify the current DIAGxx members:

The operator can enter the SET DIAG=xx command at any time after IPL.
You can specify the DIAG=xx parameter in the IEASYSxx parmlib member during IPL, and then select IEASYSxx in the LOADxx parmlib member or specify SYSP=xx in response to the SPECIFY SYSTEM PARAMETERS system message.
You can specify DIAG=xx in response to the SPECIFY SYSTEM PARAMETERS system message.

You can specify one or more current DIAGxx parmlib members during IPL. For example, a DIAG=(03,04) system parameter tells the system to use DIAG03 and DIAG04 as current members. The system processes these members in the order they are specified. For all statements other than VSM TRACK, only the last statement for that option is honored. Before changing options with SET DIAG=xx, consider issuing a D DIAG command to see what options are currently in affect. Combine the displayed options with any new request that shares the same option statement.

The VSM TRACK parameter is cumulative. For example, if you specify VSM TRACK SQA(ON) in DIAG03 and VSM TRACK CSA(ON) in DIAG04, the system turns SQA/ESQA tracking on when it processes DIAG03, and turns CSA/ECSA tracking on when it processes DIAG04 (so both are turned on). The VSM TRACE parameter, in contrast, is not. For example, if you specify VSM TRACE GETFREE(ON) SUBPOOL(127) in DIAG03 and VSM TRACE GETFREE(ON) SUBPOOL(0) ASID(1) in DIAG04, the second specification replaces the first, with the result that the system performs a GFS trace for ASID 1 only.

IBM® provides the following parmlib members:

DIAG00: Sets storage tracking on and GFS trace off. This is the default; if you do not specify a DIAGxx parmlib member during IPL, the system processes the default member DIAG00.
DIAG01: Sets storage tracking on but does not change GFS trace settings.
DIAG02: Sets storage tracking off but does not change GFS trace settings.