Configuring CICS TG for high availability

Configuring CICS® Transaction Gateway for high availability requires the creation of various JCL files and configuration files.

The common configuration file is installed in the HFS under the directory <install_path>/samples/scenarios/sc03. The sample environment files are available in the partitioned data set (PDS) install_HLQ.SCTGSAMP.

The configuration files used to define an HA group GROUPA are:

CICS Transaction Gateway configuration file

Create a CICS Transaction Gateway configuration file GroupA_GW.ini using the values suggested in the table Table 1:

  1. Define the HA group GROUPA; define the APPLIDQUALIFIER as GROUPA.
    For example:
    SECTION PRODUCT
       APPLIDQUALIFIER=GROUPA # Common group APPLID qualifier
                              # APPLID is overridden by CTGSTART_OPTS
    ENDSECTION 
  2. Define the common Gateway daemon characteristics. Edit the GroupA_GW.ini file:
    1. Define the thread pool sizes for connection managers and worker.
    2. Enable dynamic server selection policy.
    3. Enable XA support.
    4. Define the TCP/IP protocol handler using port number 4148.
    5. Define a statistics protocol handler. The port number will be overridden by the ctgstart switch -statsport.
    For example:
    SECTION GATEWAY
        maxconnect=500
        maxworker=250
        noinput=on
        xasupport=on
    
    # Enable dynamic server selection policy
        DSSPOLICY=POLICY1
    
    # Define tcp protocol handler, port 4148
        protocol@tcp.handler=com.ibm.ctg.server.TCPHandler
        protocol@tcp.parameters=connecttimeout=2000;
                                idletimeout=0;\
                                pingfrequency=10000;
                                port=4148;
                                bind=;
                                solinger=0;
    
    # Define stats protocol handler
    # Note: This port number is overridden by CTGSTART_OPTS
        protocol@statsapi.handler=com.ibm.ctg.server.RestrictedTCPHandler
        protocol@statsapi.parameters=port=;
                                     bind=;
                                     connecttimeout=2000;
                                     maxconn=5;
    ENDSECTION
  3. You must define server definitions for the Gateway daemon to communicate with CICS over IPIC in remote mode. To define the CICS server definitions for the Gateway daemon. Edit the GroupA_GW.ini file and add an IPICSERVER section for each of your CICS servers:
    • Set HOSTNAME to the name of the z/OS® machine that hosts your CICS server.
    • Set PORT to the port number that your CICS server uses to listen for incoming IPIC requests.
    For example:
    SECTION IPICSERVER = CICSA1
    DESCRIPTION=IPIC connection to CICSA1
    HOSTNAME=server.ibm.com
    PORT=4149
    CONNECTTIMEOUT=5
    SENDSESSIONS=250
    ENDSECTION
    
    SECTION IPICSERVER = CICSA2
    DESCRIPTION=IPIC connection to CICSA2
    HOSTNAME=server.ibm.com
    PORT=4150
    CONNECTTIMEOUT=5
    SENDSESSIONS=250
    ENDSECTION
    CONNECTTIMEOUT applies when the target machine is not reachable. For example, if the target LPAR is down or TCP/IP on the target LPAR has been shut down.
  4. You must define a dynamic server selection policy and associated dynamic server selection group which will be used to determine which CICS server requests are sent to.

    Edit the GroupA_GW.ini file and add a DSSPOLICY and DSSGROUP section.

    Set Servers to the name of the CICS servers to contact. Set Algorithm to the algorithm to be used for choosing a CICS server.

    For example:

    # Define dynamic server selection policy
    SECTION DSSPOLICY = POLICY1
    SUBSECTION MAPPINGS
    <NONE>=GROUP1
    ENDSUBSECTION
    ENDSECTION
    
    # Define dynamic server selection group
    SECTION DSSGROUP = GROUP1
    Servers=CICSA1,CICSA2
    Algorithm=ROUNDROBIN
    ENDSECTION

CICS Transaction Gateway environment variables

Define the characteristics specific to Gateway daemon CTGA1. Create the file CTGS03A1 with the following environment variables:
CICSCLI=<config_path>/GroupA_GW.ini
CTGSTART_OPTS=-applid=CTGA1 -statsport=4151
PATH=/bin:/usr/sbin:<java_path>/bin 
CTG_EXCI_INIT=NO 
_BPX_SHAREAS=YES
Define the individual Gateway daemon characteristics for Gateway daemon CTGA2. Create the file CTGS03A2 with the following environment variables:
CICSCLI=<config_path>/GroupA_GW.ini
CTGSTART_OPTS=-applid=CTGA2 -statsport=4152
PATH=/bin:/usr/sbin:<java_path>/bin
CTG_EXCI_INIT=NO
_BPX_SHAREAS=YES

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Timestamp icon Last updated: Tuesday, 19 November 2013


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