The system logger component

The system logger component resides in its own address space on each system in a sysplex. Some of the component processing will differ, depending on whether a given log stream is a coupling facility log stream or a DASD-only log stream. The system logger component does the following:

Provides a set of system services that allows a system logger application to use the system logger component. See z/OS MVS Programming: Assembler Services Reference IAR-XCT and the z/OS MVS Programming: Authorized Assembler Services Reference EDT-IXG.
Maintains information in the LOGR policy about the current use of log streams and if used, coupling facility list structures.
For coupling facility log streams, system logger interacts with cross-system extended services (XES) to connect to and use the coupling facility for system logger applications.
Obtains local storage buffer space. For a coupling facility log stream, local storage buffers can be used for duplexing log data. For a DASD-only log stream, local storage buffers are used as interim storage for log data before it is offloaded to DASD log data sets.
Offloads data to DASD log data sets as follows:
For coupling facility log streams, system logger offloads log data from the coupling facility to DASD log data sets as the coupling facility structure space associated with the log stream reaches the installation-defined thresholds.

For DASD-only log streams, system logger offloads log data from the local storage buffers to DASD log data sets as the DASD staging data set space reaches the installation-defined thresholds.
Automatically allocates new DASD log data sets for log streams.
Maintains a backup copy of (duplexes) log data that is in interim storage for recovery. Log data in interim storage is vulnerable to loss due to system or sysplex failure because it has not yet been hardened to DASD log data sets. System logger duplexes interim storage log data for both coupling facility and DASD-only log streams.
Produces SMF record type 88 for system logger accounting on a single system. Record type 88 focuses on the usage of interim storage (coupling facility or local storage buffers) and log stream data for a system in the sysplex. Using the record can help an installation avoid the STRUCTURE FULL or STAGING DATA SET FULL exceptions, and perform other tuning and/or capacity planning analysis.
See z/OS MVS System Management Facilities (SMF) for more information on record type 88 and system logger accounting. Sample program IXGRPT1 in SYS1.SAMPLIB shows an example of producing a report from SMF record type 88.
Ensures that:
- When the last connection from a system disconnects from the log stream, all log data written by that system to the log stream is offloaded to DASD log data sets.
  System logger also deletes any staging data sets in use for a system at this time.
- When the last connection to a coupling facility log stream in the sysplex disconnects, all coupling facility log data is offloaded to DASD log data sets and the coupling facility space is returned to XES for reallocation.
Provides recovery support in the event of application, system, sysplex, or coupling facility structure failure for coupling facility log streams. (See Recovery Performed for DASD-Only Log Streams in z/OS MVS Programming: Assembler Services Guide for information about recovery for DASD-only log streams.)