An application that is using the coupling facility might require non-volatility of the coupling facility storage. Depending on the processor on which the coupling facility is defined, you might have to provide a backup power supply to make the contents of coupling facility storage nonvolatile across utility power failures.

PR/SM™ Planning Guide describes the processor requirements for coupling facility non-volatility and the coupling facility control code MODE command. The MODE command must be set so that applications using the coupling facility can monitor its non-volatility status.