resource definition in cics

Before you can use CICS®, you must supply it with information about the resources it should use, and how to use them. Some examples of resources are:
  • Connections
  • Databases
  • Files
  • Journals
  • Journalmodels
  • Programs
  • Terminals
  • Transactions
  • Transient data queues (destinations)
Your CICS system has to know which resources to use, what their properties are, and how they interact with each other.
You supply this information to CICS by resource definition:
  1. Resource definition online (RDO): This method uses the CICS-supplied online transactions CEDA, CEDB, and CEDC. Definitions are stored on the CICS system definition (CSD) file, and installed into an active CICS system from the CSD file.
  2. DFHCSDUP offline utility: This method also stores definitions in the CSD file. DFHCSDUP allows you to make changes to definitions in the CSD file by submitting a batch job offline.
  3. Automatic installation (autoinstall): This method minimizes the need for a large number of definitions, by dynamically creating new definitions based on a "model" definition that is provided by you.
  4. System programming, using the EXEC CICS CREATE commands: You can use the EXEC CICS CREATE commands to create resources independently of the CSD file. For further information, see the CICS System Programming Reference.
  5. Macro definition: You can use assembler macro source to define resources. Definitions are stored in assembled tables in a program library, and installed during CICS initialization.
The method you use depends on the resources you want to define
Method Description Advantages Disadvantages
RDO This method uses the CEDA transaction, which allows you to define, alter, and install resources in a running CICS system. RDO is used while CICS is running, so allows fast access to resource definitions. Because CEDA operates on an active CICS system, care should be taken if it is used in a production system. Use some form of auditing as a control mechanism.
EXEC CICS CREATE system commands This method allows you to add CICS resources to a CICS region without reference to the CSD file.
  • It enables configuration and installation of CICS resources for large numbers of CICS regions from a single management focal point.
  • It also allows you to write applications for administering the running CICS system.
 CREATE commands neither refer to nor record in the CSD file. The resulting definitions are lost on a cold start, and you cannot refer to them in a CEDA transaction.
DFHCSDUP DFHCSDUP is an offline utility that allows you to define, list, and modify resources using a batch job. DFHCSDUP can be invoked as a batch program or from a user-written program running either in batch mode or under TSO.
  • You can modify or define a large number of resources in one job.
  • You can run DFHCSDUP against a non-recoverable CSD file while it is being shared between CICS regions using RLS access mode.
  • You cannot install resources into an active CICS system.
  • You cannot make updates with DFHCSDUP against a recoverable CSD file that is being accessed in RLS mode.
Autoinstall This applies to VTAM® terminals, LU 6.2 sessions, journals, programs, mapsets, and partitionsets. You set up "model" definitions using either RDO or DFHCSDUP. CICS can then create and install new definitions for these resources dynamically, based on the models. If you have large numbers of resources, much time is needed to define them, and if they are not all subsequently used, storage is also wasted for their definitions. Using autoinstall reduces this wasted time and storage. You must spend some time initially setting up autoinstall in order to benefit from it.
Macro
  • Using this method, you code and assemble macroinstructions to define resources in the form of tables.
  • This method is available only for a limited number of resource types.
 None. However, this method must be used when no other methods are available.
  • You can change the definitions contained in the tables while CICS is running, but you must stop and restart CICS if you want it to use the changed tables.
  • You must do time-consuming assemblies to generate macro tables.
For guidance on defining CICS resources, see the CICS Resource Definition Guide. For information about the DFHCSDUP utility, see the CICS Operations and Utilities Guide.
Resource definitions in the CSD are stored in groups. On a COLD or INITIAL start you specify the resource definitions that are required in a particular run of CICS by a list of groups. You can specify up to four lists of groups, using the GRPLIST=listname system initialization parameter, for installation during CICS initialization.You can also use the CEDA INSTALL command to install a resource definition or group of definitions that are defined in the CSD dynamically on a running CICS region.