Before you create and use a zHPF channel program, you must make sure that zHPF and the zHPF incorrect length facility are supported for both the device and the processor involved. An EXCP or EXCPVR request is only supported on z196 or z114 processors that support the zHPF incorrect length facility. To determine whether the processor supports zHPF, the zHPF incorrect length facility and EXCP/EXCPVR, issue the IOSZHPF macro with the DEVINFO=YES parameter. DEVINFO returns 8 bytes of information about zHPF functions supported for the device, including:

• Processor and z/OS® capabilities
  • Functions supported by the channel subsystem and online channels for a device
  • Maximum data transfer size
  • EXCPVR/EXCP virtual supported
  • Incorrect length support
• Device capabilities - You must specify DEVINFO(YES) to get device related information. Refer to the device specific architecture to interpret the device related DEVINFO=YES information.
• For those capabilities that have both a processor and device component, you must check both bits IOSDZHPF and IECDZHPF to determine if the capability is supported.

As Figure 1 shows, you must check the following in order to check to see whether the processor and device supports zHPF:

• If the processor supports zHPF
• If the processor supports incorrect length
• If the device supports incorrect length