ACT Transaction Residency Time

Transaction residency time attempts to measure the time a transaction is active in the processor for interactive systems such as CICS and IMS. The following diagram explains this measurement:
rm
Transaction residency time attempts to measure the time a transaction is active in the processor for interactive systems such as CICS and IMS. The following diagram explains this measurement:
                    task         task        _____      attached     detached        ______       |     |         |            |          |      |       |_____|         |            |          |______|          |         |  |            | |  input   |            |            |              |  output  message  -------->|  |<__________>| | ------------ message                         Transaction                          Residency
When a message enters the system, it is transmitted to the CPU, where it resides until the processing completes. The period between the time of input and the time the task is attached is not included in transaction residency time, nor is the period between the time the task is detached from the CPU and the time the output message is received.
Because transaction residency time is dependent on the multiprogramming mix, it varies with the performance of the computer and the number of other transactions in the system. As the same task does not always have the same transaction residency time, it is an inconsistent, and therefore unsatisfactory, method of measurement.