Once all subsystems are ended, you can power down the system. This is done using the Power Down System (PWRDWNSYS) command.
The PWRDWNSYS command turns off the system. Like the ENDSBS command, it has an option parameter that accepts either *CNTRLD or *IMMED. This parameter is valuable only if you have not ended the subsystems beforehand. If all subsystems are ended, the value you select in this parameter is irrelevant.
The RESTART parameter is more important. If you specify *NO, the system shuts itself down. The system removes electrical power from all the CPU components.
If you specify RESTART(*YES), the system goes through the motions of powering down but, at the last moment, it starts again. This is the way to perform an IPL without shutting down the system entirely.
Remember that shutting down the system using PWRDWNSYS doesn't cut electrical power from peripheral devices such as display stations and printers. You still have to turn those off using their power switches.