Modifying the CDC for Db2 for z/OS® configuration control data set

CDC Replication requires that certain configurable settings be specified prior to its execution, so that they can be read and processed during initialization of the CDC Replication address space. These configurable settings are specified as values of keywords in statements in the CDC Replication configuration control data set.

Note: Comments are allowed in any statement in the configuration control data set. Comments are indicated by an asterisk ('*') in column 1, or by enclosing the entire comment between the '/*' and '*/' symbols. Blank lines in statements are ignored.

During the installation process, the configuration control data set will have been allocated, and populated with sample configuration control data set members. In this section the data set is referred to as the CHCCNTRL data set to distinguish it from the SCHCDATA from which the samples have been copied. Required members are provided in the sample data set. If you wish to use one for which no sample exists, simply create it.

Most of the sample configuration control data set members have a two-character suffix of xx. These suffixes should be replaced with the value assigned to the <ConfigSuffix> placeholder resolved in the CHCPROC JCL procedure. For example, if the <ConfigSuffix> placeholder has been assigned a value of 01, then rename CHCCFGxx, CHCCMMxx, CHCDBMxx, CHCLDRxx, and CHCUCSxx to CHCCFG01, CHCCMM01, CHCDBM01, CHCLDR01, and CHCUCS01, respectively. The CHCTMZON sample configuration control data set member is the only one that does not require a suffix. Simply copy the distributed sample member to the execution-level configuration control data set.

Although these members may have been renamed through the above example to incorporate the value of the <ConfigSuffix> placeholder into their names, the following sections will continue to refer to them with the original, distributed names. In other words: CHCCFGxx, CHCCMMxx, CHCDBMxx, CHCLDRxx, and CHCUCSxx.

Each member provides configuration settings to different components of CDC Replication. The members are:

  • CHCCFGxx—Contains general product configuration control statements.
  • CHCCMMxx—Contains communications configuration control statements. This member provides CDC Replication with information about how it will employ TCP/IP for communication
  • CHCDBMxx—Contains DBMS configuration control statements. This member provides CDC Replication with information about how it will locate and employ the Db2® Subsystem to and from which it will replicate data.
  • CHCTMZON—Contains a time zone description control statements. These are used when communicating with other instances of CDC Replication in other countries or regions.
  • CHCLDRxx—Contains a DB2LOADER configuration control statement. This member provides CDC Replication with default values for use on a Db2 LOAD Utility control statement that CDC Replication target environment will use when it is internally invoking the Db2 LOAD Utility to load data into a table that is being Refreshed.
  • CHCUCSxx—Contains configuration control statements necessary to work with Unicode Conversion Services (UCS). This member provides CDC Replication with information about using Unicode Conversion Services when performing translation of text data from the code page of the source server to the code page of the target server. The distributed member contains only comments, and can be modified if you need to provide additional CCSIDMAP and IANAMAP control statements, should there be new code pages that have yet to be incorporated into the set internal to CDC Replication.

If more than one copy of CDC Replication will be executed, then additional copies of the configuration control data set members can be produced, each set distinguished with a different, common suffix. Each distinct set can provide tailored configurable settings to a different copy of CDC Replication that is accessing them. All copies of CDC Replication can access the same configuration control data set, but use a different set of configuration control data set members.

The two character suffix (xx) should be changed to the value of the <ConfigSuffix> placeholder. The <ConfigSuffix> placeholder will also appear in the CHCPROC member of the SCHCCNTL data set. Replacing the <ConfigSuffix> placeholder in this member will provide CDC Replication with the information it needs to locate and process the proper CHCCFGxx member of the configuration control data set.

If a keyword in a statement is assigned an invalid value, the default value for that keyword is used where applicable.

It is good practice when assigning configuration parameters to confirm that the values intended are the values actually used by the product. Upon startup, the CHC tasks write the values of the various configuration parameters used to the CHCAUDIT data set. These should be reviewed against the settings in the configuration files and any unintended settings (such as typos) corrected.

The values set in configuration parameters can also be viewed (but not updated) on the Datastore Properties dialog in Management Console.