INTVAL and SYNCVAL parameters

SMF provides the INTVAL and SYNCVAL parameters. The INTVAL parameter can be used to set the interval at which the type 89 records are created only when two conditions are met:

You have specified the SMF suboption of INTERVAL.
INTVAL has a value that divides evenly into 60 minutes.

Although SYNCVAL can not change type 89 record's synchronization with the start of the hour, SYNCVAL, INTVAL and INTERVAL can influence the way that SMF reports task and function related time in the type 89 record, for those products collecting task or function time. See the topic “Collecting Your Own Data Using the IFAUSAGE Macro” in z/OS MVS System Management Facilities (SMF). for a description of task and function time. SMF reports the exact task or function time that occurred during the measurement interval only when SYNCVAL has a value of 0, INTVAL has a value that divides evenly into 60 minutes, and the INTERVAL value divides evenly into the INTVAL value. Unless all of these conditions are true, SMF must apportion the task time that it collects across two reporting intervals, rather than precisely reporting the time in the appropriate measurement interval. (SMF always reports the time collected on an address space basis to the correct measurement interval regardless of the INTERVAL, INTVAL, and SYNCVAL parameters.)

Thus, IBM® recommends that installations running OS/390® or z/OS® use:

An INTVAL value that divides evenly into 60
A SYNCVAL of 0
An INTERVAL parameter with the SMF option or an INTERVAL value that divides evenly into the INTVAL value.

Each of the examples shown in Table 1 meet all the recommended conditions and will, therefore, precisely report all of a product's task and function time under the interval in which it was collected.

Table 1. Example: Valid INTVAL, SYNCVL, and INTERVAL specifications
Example 1	Example 2	Example 3
`INTVAL(15) SYNCVAL(00) INTERVAL(SMF,SYNC)`	`INTVAL(30) SYNCVAL(00) INTERVAL(003000)`	`INTVAL(60) SYNCVAL(00) INTERVAL(SMF,SYNC)`