Building Recall Exit Lists

When selecting and prioritizing target volumes for recalled data sets, the recall exit builds three lists related to candidate volumes:

Target volume candidate list
Target volume choice list
Target volume unlike attribute array list

Figure 1 shows the recall exit parameter list and the three associated recall target volume lists.

Figure 1. Recall Target Volume Data Structures

As described in Table 1, the target volume candidate list has the following four components:

Unlike attribute array address
Number (unlike)
Number (like)
Volume serial (like) or volume serial (unlike)

Table 1. Target Volume Candidate List
Offset	Length or Bit Pattern	Description
-6	4	Unlike attribute array address The address of an array containing entries corresponding to candidate volumes with unlike DFSMShsm attributes
-2	2	Number (unlike) A halfword binary number indicating the number of volume serial numbers for unlike volumes in the candidate list
0	2	Number (like) A halfword binary number indicating the number of volume serial numbers for like volumes in the candidate list
2	6	Volume serial (like) A 6-byte candidate volume serial number.
8	6	Volume serial (like) A 6-byte candidate volume serial number.
14	6	Volume serial (like) An array of 6-byte candidate volume serial number.
20	6	Volume serial (like) Each entry is a 6-byte candidate volume serial number.
(See note)	6	Volume serial (unlike) A 6-byte candidate volume serial number.
(See note)	6	Volume serial (unlike) A 6-byte candidate volume serial number.
(See note)	6	Volume serial (unlike) Each entry is a 6-byte candidate volume serial number.
Note: The offset of the first unlike volume serial number is 2 + 6 × the number of like volume serials; each subsequent offset is 6 greater.

The contents of the target volume candidate list differs according to the way pools of target volumes are established and the subparameters of the SETSYS RECALL command. Details about volume pools can be found in the z/OS DFSMShsm Storage Administration. Data sets are recalled to one of three target volume categories:

Volumes associated with a user-defined pool of volumes
Volumes with like source and target volume attributes
Volumes with unlike source and target volume attributes