SET CONTROLLER selects the controller device-name as
                the default controller. The device name has the format
                ddcu, where:

                - dd is the device code.

                - c is the controller designation A through Z.

                - u is the unit number (0 through 9999).

                Note: SET CONTROLLER command is synonymous to SET
                      ADAPTER command.

                Format:
                        CONTROLLER [DEVICE-NAME:] / <qualifiers>