Save and Restore option to start controlling subsystem

As an example, upgrading to a new release would be a likely use of this new menu option.  IBM recommends a full Save (GO SAVE 21), which is usually done just prior to starting the upgrade and within the same maintenance window.  Prior to this enhancement, in order to avoid starting controlling subsystems and potentially bringing the system live again, the operator would have to specify to "Prompt for commands" on the GO SAVE 21.  This is known as an "attended Save", where the operator needed to confirm each Save command to progress through the Save operation.  Alternatively, if the operator did NOT prompt for commands, the GO SAVE 21 would automatically start the controlling subsystems at the end, and the operator would need to take an overt action to quickly bring the system back to a restricted state. This could be complicated, as several services might have been started as a result of starting the controlling subsystem, and ending them gracefully might take a long time, plus there was risk that changes could have been made in this short time.

With this 7.4 enhancement, the user can now specify "Start controlling subsystem = N" to allow the Save to run unattended. This result may include less intervention from the operator for running the save operation unattended, as well as possibly reducing the overall window from not having to end all the services and applications that may get started as a result of starting the controlling subsystem.  It also closes the opportunity for data changes, thus making the full Save consistent with the system state, with no delta between the Save data and the data on the system.