Use request type FENCE to prevent unintended access, through Soft Fence, of a device, a set of devices in an LSS or all devices in an LSS. This invokes ANTRQST ILK=PPRC REQUEST=FENCE.
If you omit the parameter, the command is issued to the device that is logically in subchannel set 0. If a swap has occurred, this could be the device that was defined in an alternate subchannel set in the I/O configuration (IODF), with HCD.