Configuring the logstream for the CSL OM audit trail

The IMS IVP defines a logstream with parameters set to apply generally to most users. Depending on the configuration and requirements of your installation, you might consider changing these parameters when you define an OM audit trail logstream.

Parameters set by the IVP to consider changing include:

LS_SIZE(200): LS_SIZE controls the size of the offload data sets. Your installation might benefit from larger data sets.
LOWOFFLOAD(20): LOWOFFLOAD affects the frequency of offloads. A lower LOWOFFLOAD percentage, such as 0, generally means that offloads occur less frequently and, unless the logstream is browsed in realtime, should be the most efficient.
HIGHOFFLOAD(50): HIGHOFFLOAD affects the frequency of offloads. A higher HIGHOFFLOAD value, such as 70, generally means that offloads occur less frequently, which improves efficiency.

The IMS IVP also does not define the system logger to duplex to staging data sets. If your installation requires a higher level of data redundancy than is provided with MVS dataspace duplexing then consider enabling external duplexing by adding STG_DUPLEX(YES) to the definition below, along with the DUPLEXMODE parameter, which defines the conditions in which the duplexing occurs. However, the higher level of data redundancy must be weighed against the performance impact of the duplexing option.

The IMS IVP defines a logstream with the following parameters:

DEFINE STRUCTURE NAME(IMSOM2Q01)          
         LOGSNUM(1)                       
         AVGBUFSIZE(4000)                 
         MAXBUFSIZE(32760)                
                                          
DEFINE LOGSTREAM NAME(SYSLOG.OM2Q01.LOG)  
         STRUCTNAME(IMSOM2Q01)            
         HLQ(IXGLOGR)                     
         LS_STORCLAS(LOGGER1)             
         LS_DATACLAS(LOGGER1)             
         LS_MGMTCLAS(LOGGER)              
         LS_SIZE(200)                   
         LOWOFFLOAD(20)
         HIGHOFFLOAD(50)

Recommendations:

Set the logstream maximum buffer size (MAXBUFSIZE) to 32,760 bytes. This setting ensures that all command and command response data is written to the audit trail. A lower setting will result in the truncation of some OM Audit Trail log records.
Dedicate a log stream to the OM audit trail.