Allocating Space with SPACE and AVGREC

You can also allocate space by using both the SPACE and AVGREC JCL keywords together. In the following examples, the average length is 70␠000 bytes for each member, each record in the member is 80 bytes long, and the block size is 23␠200. Using the AVGREC keyword changes the first value specified in SPACE from the average block length to average record length. These examples are device independent because they request space in bytes, rather than tracks or cylinders. They would allocate approximately the same amount of space as the previous examples (about 75 tracks if the device were a 3380 disk).

   SPACE=(80,(44,,10)),AVGREC=K
 
   SPACE=(80,(43500,,10)),AVGREC=U

Although a secondary allocation increment has been omitted in these examples, it could have been supplied to provide for extension of the member area. The directory size, however, cannot be extended. The directory must be in the first extent.

Recommendation: The SPACE parameter can be derived from either the data class, the LIKE keyword, or the DD statement. Specify the SPACE parameter in the DD statement if you do not want to use the space allocation amount defined in the data class.

Related reading: For more information on using the SPACE and AVGREC parameters, see Allocating Space on Direct Access Volumes , and also see z/OS MVS JCL Reference and z/OS MVS JCL User's Guide.