Initial or cold start

During an initial or cold start, CICS creates system tables by installing groups named in the list or lists named by the GRPLIST system initialization parameter. If you installed a group with the INSTALL command during the previous CICS execution, you must add its name to a list if you want it to be installed during a cold start.

If you usually use START=COLD at CICS initialization, installing by means of a list will probably be your standard way of making resource definitions available to CICS. Use of the INSTALL command is a supplementary method, which you could find very useful when testing a system, or if an unexpected need for a resource arises when CICS is running.

You may not want to use the RDO transactions in a production system, for security or performance reasons. In this case, the CSD file is shared by both systems, but is read-only in the production system. You define all your production resources using your development system, and install them in the production CICS system when you cold start it.