Initially accessing the RECON data sets
When a job needs to read the RECON data set, the RECON data set must be opened. When three RECON data sets exist, DBRC determines which two are the active RECON data sets and which is the spare data set.
The following table shows how this determination is made. The columns in the table have the following meanings:
- In the DD statement column, RECONA, RECONB, and RECONC represent the RECON1, RECON2, and RECON3 DD statements in no particular sequence.
- The data set status column indicates the status of the data set during open time.
- The data set use column indicates how DBRC assigns the data set.
| Case | DD statement | Data set status | Data set use | DBRC selection criteria |
|---|---|---|---|---|
| 1 | RECONA | Create Mode | Copy1 | Not selected until INIT.RECON command is specified |
| RECONB | Create Mode | Copy2 | Not selected until INIT.RECON command is specified | |
| RECONC | Create Mode | Spare | ||
| 2 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | Create Mode | Copy2 | Produced from Copy1 | |
| RECONC | Create Mode | Spare | ||
| 3 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Copy2 | Current copy of RECON | |
| RECONC | Create Mode | Spare | ||
| 4 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Unused | Older copy than RECONA | |
| RECONC | Create Mode | Copy2 | Produced from Copy1 | |
| 5 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Unused | Older copy than RECONA | |
| RECONC | RECON | Unused | Older copy than RECONA | |
| 6 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Copy2 | Current copy of RECON | |
| RECONC | RECON | Unused | Older copy than RECONA | |
| 7 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | Create Mode | Copy2 | Produced from Copy1 | |
| 8 | RECONA | Create Mode | Copy1 | Not selected until INIT.RECON command is specified |
| RECONB | Create Mode | Copy2 | Not selected until INIT.RECON command is specified | |
| 9 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Copy2 | Current copy of RECON | |
| 10 | RECONA | RECON | Copy1 | Current copy of RECON |
| RECONB | RECON | Unused | Older copy than RECONA | |
| 11 | RECONA | Create Mode | None | Discontinue processing |
| 12 | RECONA | RECON | Copy1 | Current copy of RECON |
Case 4 is the situation where two RECON data sets are available, but one is now out of date. DBRC does not use the out-of-date RECON data set. Instead, it copies the up-to-date RECON data set to the spare data set.
Only one RECON data set is available in cases 5, 10, and 12. If you have specified the STARTNEW parameter of the INIT.RECON or CHANGE.RECON command, processing continues with one RECON data set. Otherwise, processing ends. If another DBRC instance is active and parallel RECON access is enabled, the new DBRC must be able to access the same data sets (both in name and active count) as the existing DBRC regardless of the STARTNEW parameter. If the new DBRC does not access the same data sets, a WTOR will be issued for online DBRC regions and processing will end for non-online DBRC regions.