Optionally define log streams to keep a record of the check output

IBM Health Checker for z/OS retains only the check results from the last iteration of a check in the message buffer. If you want to retain a historical record of check results, which is optional, but a good idea, you can define and connect to a log stream. When you have a log stream connected, the system writes check results to the log stream every time a check completes.

Note that most of our instructions are for coupling facility log streams, which are suggested. For information about setting up a DASD-only logstream, see the "Planning for system logger applications" section of z/OS MVS Setting Up a Sysplex

Do the following to define log streams:

Plan for setting up log streams, including allocation of coupling facility and DASD space. Careful planning of DASD and coupling facility space is important because if the log stream fills up, no additional data will be written to it and data will be lost. See the "Planning for system logger applications" section of z/OS MVS Setting Up a Sysplex. Keep in mind the following:
- Define either:
  - One log stream for each system.
  - One log stream for multiple systems to use.
- HZS must be the first letters of log stream names and structures you define. For example, you might define a log stream name of HZSLOG1.
- System logger requires at least a base sysplex configuration in your installation.
- System logger requires SMS to be active, in at least a null configuration, even if you do not use SMS to manage your volumes and data sets. See the "Plan DASD space for system logger" section of z/OS MVS Setting Up a Sysplex.
Set up security for log streams:
1. You will accomplish most of the security set up needed for the log stream when you set up security for the IBM Health Checker for z/OS super User ID in Setting up security for the IBM Health Checker for z/OS started task.
2. The user who will be setting up log stream and structure definitions for the IBM Health Checker for z/OS log stream using the IXCMIAPU Administrative Data Utility program must have authorization to a number of resources. See the Define Authorization for system logger resources section of z/OS MVS Setting Up a Sysplex.
3. See Security for printing check output from a log stream to set up security access for users to the HZSPRINT output, if you will be using HZSPRINT to print log stream data.
Enable log streams in one of the following ways:
- Use the MODIFY command:
```
f hzsproc,logger=on,logstreamname=logstreamname
```
- Use the LOGGER parameter in the HZSPRMxx parmlib member:
```
LOGGER(ON) LOGSTREAMNAME(logstreamname)
```
  To disable a log stream, issue the following MODIFY command:
```
f hzsproc,logger=off
```
To display check output from a log stream, use either:
- The HZSPRINT utility - See Optionally set up the HZSPRINT utility.
- SDSF - See Using SDSF to manage checks.

The following examples show our log stream definitions:

CFRM policy definition: The following example shows a log stream and structure definition defined in the CFRM policy using the administrative data utility, IXCMIAPU:
```
STRUCTURE NAME(HZS_HEALTHCHKLOG) SIZE(9000)
   PREFLIST(CF25, CF01C, CF1)       
```
The value defined for SIZE should be no less than 8000 to ensure adequate space for check data. For more information, see:
- "Define the coupling facility structures attributes in the CFRM policy couple data set" inz/OS MVS Setting Up a Sysplex
- IBM® recommends that you use the following web-based CFSizer tool to estimate an appropriate structure size
```
http://www.ibm.com/systems/support/z/cfsizer/
```
.

LOGR policy definitions:

The following example shows a coupling facility and log stream structure definition in the LOGR policy using the administrative data utility, IXCMIAPU:

DEFINE STRUCTURE NAME(HZS_HEALTHCHKLOG)              
       LOGSNUM(1)                                    
       MAXBUFSIZE(65532)                             
       AVGBUFSIZE(1024)

DEFINE LOGSTREAM NAME(HZS.HEALTH.CHECKER.HISTORY) 
          DESCRIPTION(HEALTH_CHECK_RPT)              
          STRUCTNAME(HZS_HEALTHCHKLOG)               
          STG_DUPLEX(NO)                             
          LS_DATACLAS(NO_LS_DATACLAS)                
          LS_MGMTCLAS(NO_LS_MGMTCLAS)                
          LS_STORCLAS(NO_LS_STORCLAS)                
          LS_SIZE(4096)  
         AUTODELETE(YES)
         RETPD(14)     
         HIGHOFFLOAD(80)
         LOWOFFLOAD(0)  
         DIAG(NO)

Note that the IBM Health Checker for z/OS® structure and log stream names must begin with HZS.

The following example shows a DASD-only log stream definition in the CFRM policy using the administrative data utility, IXCMIAPU. Note that the values you define for a DASD-only log stream in your installation may be different.

DEFINE LOGSTREAM NAME (HZS.HEALTH.CHECKER.HISTORY)
     DASDONLY(YES)
     MAXBUFSIZE(65532)
     HIGHOFFLOAD(80)
     LOWOFFLOAD(20)
     STG_SIZE(2000)
     LS_SIZE(1000)
     LS_DATACLAS(lsdataclas)   
     LS_STORCLAS(lsstorclas) 
     STG_DATACLAS(stgdataclas)   
     STG_STORCLAS(stgstorclas)

For more information on the LOGR couple data set, see "Add information about log streams and coupling facility structures to the LOGR policy" section of z/OS MVS Setting Up a Sysplex.