When the application program issues BLDL, BPAM opens the specified UNIX file and establishes a connection. BPAM retains the logical connection until the program issues STOW DISC or CLOSE, or ends the task.

The BLDL macro reads one or more UNIX directory entries into virtual storage. Place UNIX file names in a BLDL list before issuing the BLDL macro. For each file name in the list, BLDL returns a three-byte simulated relative track address (TTR). This TTR is like a simulated PDS directory entry. Each open DCB has its own set of simulated TTRs for the UNIX files. This TTR is no longer valid after the file is closed.

You can alter the sequence of directories searched if you supply a DCB and specify START= or STOP= parameters. These parameters allow you to specify the first and last concatenation numbers of the data sets to be searched.

If more than one filename exists in the list, the filenames must be in collating sequence, regardless of whether the members are from the same or different UNIX directories, PDSs, or PDSEs in the concatenation.

You can improve retrieval time by directing a subsequent FIND macro to the BLDL list rather than to the directory to locate the file to be processed. The FIND macro uses the simulated TTR to identify the UNIX file.

The BLDL list must begin with a 4-byte list descriptor that specifies the number of entries in the list and the length of each entry (12 to 76 bytes). The first 8 bytes of each entry contain the file name or alias. The next 6 bytes contain the TTR, K, Z, and C fields.

Restriction: BLDL does not return user data or NOTE lists in the simulated PDS directory entry.