Checking for timer synchronization

Several processors can share work in a data processing complex. Each of these processors has access to a TOD clock. Thus, when work is shared among different processors, multiple TOD clocks can be involved. However, these clocks might not be synchronized with one another. The External Time Reference (ETR) is a single external time source that can synchronize the TOD clocks of all processors in a complex.

For programs that are dependent upon synchronized TOD clocks in a multi-system environment, it is important that the clocks are in ETR synchronization. Use the STCKSYNC macro to obtain the TOD clock contents and determine if the clock is synchronized with an ETR. STCKSYNC also provides an optional parameter, ETRID, that returns the ID of the ETR source with which the TOD clock is currently synchronized.