When a user goes into the shell environment using the OMVS command from TSO/E, very long TSO/E response times (several seconds) might be recorded. This can affect those WLM goals for TSO users that are based on response time.

Normally, a TSO/E transaction starts when a user enters a command and ends when the command is completed. After the TSO/E command completes, a TGET WAIT is issued, indicating that the current transaction has completed and a new transaction will start when there is more work to be done.

In the OMVS shell environment, however, things work a little differently. A transaction starts when a command is issued from the terminal. After the command is issued, polling is done to wait for output to return from the command. Every half second, there is a test for output and a test (TGET NOWAIT) for terminal input. This goes on for 20 seconds before the session goes into INPUT mode and does a TGET WAIT for terminal input only. TGET NOWAIT does not end the current transaction unless terminal input is found. If there is no more terminal input for over 20 seconds, the transaction does not end until the TGET WAIT is issued and the session goes into INPUT mode.

In effect, TSO/E users in the shell environment can experience response times of up to 20 seconds, often with little service consumption. Response times under 20 seconds occur only when users immediately enter the next command.