To implement the MVS System Logger, do the following:

1. Use the IBM administrative data utility program IXCMIAPU to create or update the Coupling Facility Resource Management (CFRM) policy.
2. Define a Coupling Facility and a 1000K Coupling Facility structure. Use the 1- through 16‑character Coupling Facility structure name for the STRUCTNC subparameter in Step 7.5 – CMEM Sysplex configuration parameters (optional).
3. Set the parameters for the structure and log stream as shown in the following table:

   Table 62 Parameter values for the structure and log stream

   Parameter	Value
   AUTODELETE	NO
   RETPD	0
   AVGBUFSIZE	144
   STG_DUPLEX	For a regular log stream – YES For a DASD-only log stream – NO
   DUPLEXMODE	For a regular log stream – COND For a DASD-only log stream – not applicable
   LS_SIZE	128

For detailed information about how to manage the CFRM policy, see Chapter 4, "Managing Coupling Facility Resources" and Appendix B, "Administrative Data Utility" in the IBM document z/OS V1Rx MVS Setting Up a Sysplex.

The MVS System Logger can also be used with DASD-only log streams. The main difference between Coupling Facility and DASD-only log streams is the storage medium used by the System Logger to hold interim log data.

• The Coupling Facility log stream uses Coupling Facility structures.
• The DASD-only log stream uses LOGR buffers.

To use DASD-only log streams you should set the value of the STRUCTNC CMEM installation parameter to DASDONLY. For more information, see Step 7.5 – CMEM Sysplex configuration parameters (optional).

Note: Only applications from the same system (LPAR) can connect simultaneously to the DASD-only log streams. If you are using DASD-only log streams, Control‑M, CMEM or Control‑O, and IOADDC (the CONNECT DIRECT interface) must all be running in the same LPAR.