The extra CPUs are invisible to BS2000 guest systems. They can only be used via VM2000 commands – see the “VM2000” manual [60].
With VM2000, in addition to the normal virtual CPUs (whose number is specified when configuring the VM), all guest systems are assigned as many virtual spare CPUs as the Server Unit configuration has real spare CPUs. The virtual CPU that fails when the real CPU it is currently running on fails is replaced by the affected guest system by a virtual spare CPU.
This is especially important for the availability of guest systems that only have one CPU assigned since such systems without a spare CPU are terminated immediately when CPU errors occur while it is running. With a (virtual) spare CPU, there is a realistic chance when a failure occurs that the guest system will be able to continue operation without interruption after an internal CPU reconfiguration.