JCL DD statements: Use different parameters for SMS data sets

The Storage Management Subsystem (SMS) automates the use of storage for data sets. The use of SMS, which is optional, affects the JCL you code on DD statements for SMS-managed data sets.

In a z/OS® system, data management involves tasks that include the allocation, placement, backup, recall and deletion of data sets. These activities can be done either manually or through the use of automated processes. Several of these activities can be done manually through the use of JCL.

Part of the z/OS storage management product, the Storage Management Subsystem (SMS), automates the use of storage for data sets. With SMS, the z/OS system programmer or storage administrator may, for example, create model data definitions for typical data sets, so that SMS automatically assigns attributes to data sets when they are created. The data sets allocated through SMS are called system-managed data sets or SMS-managed data sets.

Before you start using JCL to work with data sets, you should know whether your company uses SMS for the data sets you will be creating or using. If your company does use SMS, you do not need to code certain DD statement keywords in your JCL.

For example, suppose you want to create a new data set named DATA.LIST. If SMS is active, you could use JCL like this:

//NEWDS DD  DSN=HLQ.DATA.LIST,
//          DISP=(NEW,KEEP),
//          DATACLAS=DSCLAS01,
//          STORCLAS=STRCLS20

In this case, z/OS can use characteristics from predefined data and storage classes when it creates the DATA.LIST data set for you.

If SMS is not active or not in use, you need to manually specify the space requirements and storage location for the new data set, and your JCL would look like this or something even more complicated:

//NEWDS DD  DSN=HLQ.DATA.LIST,
//          DISP=(NEW,KEEP),
//          SPACE=(CYL,(1,1)),
//          UNIT=SYSDA,
//          VOL=SER=SHARED