Scanning for UCBs

There are two methods to scan for UCBs: the UCBSCAN macro and the UCB scan service. IBM® recommends that you use the UCBSCAN macro rather than the UCB scan service.

The UCBSCAN macro is the general method for scanning UCBs. You can use it to scan for any UCB, including UCBs for dynamic devices, UCBs with 4-digit device numbers, and UCBs that reside above 16 megabytes. See Obtaining UCB information (general methods) for more information about the UCBSCAN macro.

The UCB scan service is an older, limited method. It scans only for UCBs for static or installation-static devices, UCBs with 3-digit device numbers, and UCBs residing below 16 megabytes. The limited UCB scan service is described in Obtaining UCB information (limited method).