Each OAM SMF record has a function start and end time in the common OAM product section. The start and end times are in fields R85PSTRT and R85PENDT respectively, and they are presented in z/Architecture® STORE CLOCK (STCK) instruction format.
The starting time of the OAM function is obtained as soon as possible so that the elapsed time of the function includes as much OAM processing time as possible.
The ending time of the OAM function is obtained as soon as possible to the end of the function so that the elapsed time of the function includes as much OAM processing time as possible. However, because the function end time (in field R85PENDT) is set and the elapsed time (in field R85PRESP) is calculated prior to passing the record to SMF for recording, the elapsed time does not include the time required to invoke SMF and the time required to copy the record into the SMF buffers.