You can use the UCBINFO macro to obtain information from a UCB
for a specified device. You can use UCBINFO to obtain:
- A count of the UCBs for a device class
- Reasons why a device is offline
- Device path information
- Channel path type information
- A copy of the UCB prefix extension
- Information about the alias UCBs for a parallel access volume.
When you call UCBINFO, you provide the device number of the device
for which you want the information.