Required specifications

The following requirements are necessary when you specify journal data sets:

Allocate journal data sets on disk volumes. Each journal data set must be a fixed-block SAM data set with the following attributes:
```
DCB=(RECFM=FB,LRECL=7680,BLKSIZE=7680,DSORG=PS),SPACE=(TRK,(1200,0)) 
```
Note: If the LRECL and BLKSIZE are not set to 7680, the system data mover will attempt to force the allocation to this size.
Specify at least two journal data sets. If you allocate less than the maximum number of journal data sets, XRC issues the following message:
```
 DATA SET SYS1.XCOPY.session_id.JRNLnn NOT IN CATALOG OR CATALOG
       CANNOT BE ACCESSED
```
A high-level qualifier name can replace SYS1 in the example. XRC issues the above message for the first journal data set that is not found, even if there are two or more journal data sets allocated.
Do not use compression algorithms on journal data sets.
Observe the following when naming journal data sets:
- Specify up to eight alphanumeric characters for the session_id portion of the journal data set name. Use the same name that you will specify with the session_id parameter of the XSTART command.
- Name the journal data sets contiguously with a number, nn, beginning at 01 up to a maximum of 16.
  Example: If you define journal data sets 01, 02, and 04, XRC ignores data set 04 because you did not define data set 03.