System logger requires that you have SMS installed and its address space active at your installation on each system where system logger is expected to run. This is true even if you do not use SMS to manage your volumes and data sets. SMS must be active because system logger uses VSAM linear data sets. If the SMS address space is not active when you attempt to use a system logger application, system logger issues system messages that indicate allocation errors and the application will not be able to use the logger function.

If you do not use SMS to manage your data sets, you can set up a minimal SMS configuration to provide an environment for SMS. The minimal SMS configuration allows you to define model allocation characteristics for data sets. See z/OS DFSMS Implementing System-Managed Storage for information about establishing a minimal SMS configuration.

Set up the SMS environment to manage DASD log data sets and DASD staging data sets. See z/OS DFSMSdfp Storage Administration for creating the following SMS classes:

1. Storage groups identifying the volumes to be used for data set allocation.
2. Storage classes to describe the performance characteristics for the data sets.
3. Data classes to specify the data set characteristics and size of the data sets.
4. Management classes to specify the migration characteristics of the data sets. The data sets might be migrated to hierarchical storage manager (HSM) or archived. See Log stream data set migration and recall considerations.
5. Automatic class selection (ACS) routines to assign the storage groups, classes, data classes and management classes, based on data set name when the DASD data sets are allocated.

You can specify the SMS characteristics for log and staging data sets in a number of ways, depending on how an installation is set up. For example, there might be installation written automatic class selection (ACS) routines to assign classes for DASD data sets, or you can specify the SMS characteristics for DASD log and staging data sets in the LOGR policy. To define the SMS characteristics in the LOGR policy, see Specifying SMS data set characteristics for DASD data sets.

If you specify EXT on data set name type on your DFSMS data class, consider specifying Extended Addressability as 'N' to prevent logger from using data sets larger than 4GB in size. If you specify Extended Addressability as 'Y', ensure the data sets you allocate are less than 4GB.

With PTFs for OA37972 applied, if the allocation is over 4GB, logger will deallocate the data set and try to allocate a data set near 3.5GB to maintain log stream availability. See Testing log data set parameter modifications for more information.