Activate the LOGR subsystem

The LOGR subsystem allows you to read log stream output without having to re-write your existing applications. For example, you might have existing applications that read logrec data in data set format and do not support the log stream format. The LOGR subsystem lets you access log stream data in data set format.

If your installation chooses to use the LOGR subsystem to read log stream output, you must activate it before using the log stream. Activate the LOGR subsystem using one of the following methods:

In the IEFSSNxx parmlib member, add the following:
```
SUBSYS SUBNAME(LOGR) INITRTN(IXGSSINT)
```
Note that the new format for defining the LOGR subsystem is required (you cannot use the old format). Because IEFSSNxx parmlib members cannot contain the new and old format definitions in the same IEFSSNxx parmlib member, you might need to define a new parmlib member for the LOGR subsystem and concatenate it with other IEFSSNxx parmlib members.
Use the SETSSI command to add the subsystem dynamically:
```
SETSSI ADD,SUBNAME=LOGR,INITRTN=IXGSSINT
```
The value specified for SUBNAME is defined by the installation; it does not have to be LOGR. Make sure, however, that the subsystem name specified in the SUBNAME parameter matches the corresponding name in the SUBSYS option in the JCL.

Note that you cannot issue either the SETSSI ACTIVATE or SETSSI DEACTIVATE command for the LOGR subsystem.

For more information about the topics described in this section, see the following references:

See z/OS MVS Programming: Assembler Services Guide for information about using the LOGR subsystem.
See z/OS MVS Initialization and Tuning Reference for information about the IEFSSNxx parmlib member.
See z/OS MVS System Commands for information about the SETSSI command.
See z/OS MVS Installation Exits for information about the LOGR subsystem exit.