Installing the CICS SVCs

Install the current level of the CICS® Type 3 SVC, DFHCSVC, and the high performance option (HPO) SVC before you attempt to start a region.

If IBM® changes the Type 3 SVC, for example at a new release or because of a service update, you must reinstall the current level of the CICS Type 3 SVC into the link pack area (LPA) and perform an IPL with the CLPA option.

To install the CICS Type 3 SVC, define the CICS SVCs to z/OS®, install the DFHCSVC module into the LPA, and specify the DFHCSVC number on the CICSSVC system initialization parameter.

Alternatively, if you have the required authorization, you can use the DFHCSVCU utility program to install the CICS Type 3 SVC dynamically, without the need to perform an IPL of the z/OS system. For further information about running programs that require APF authorization, see Managing system security in z/OS MVS Initialization and Tuning Reference. For further information about the DFHCSVCU utility program, see DFHCSVCU.

Defining the CICS SVCs to your z/OS system

Define both the CICS Type 3 SVC and the HPO SVC to your z/OS system by specifying SVCPARM statements. You define the CICS SVCs in an IEASVCxx member of the SYS1.PARMLIB library, using SVCPARM statements. See z/OS MVS Initialization and Tuning Guide and z/OS MVS Initialization and Tuning Reference for a description of the SVCPARM statements.
If you are using the default SVC numbers, the following CICS entries are shown:
```
SVCPARM 216,REPLACE,TYPE(3),EPNAME(DFHCSVC)
SVCPARM 215,REPLACE,TYPE(6),EPNAME(DFHHPSVC)  [Only required for HPO]
```
For the current SVC modules, you specify the EPNAME parameters as in the sample CICS entries.
If you have a version of the DFHHPSVC module from an earlier release of CICS already link-edited into your z/OS nucleus, you do not have to replace it with the latest version. Versions of the DFHHPSVC module from earlier releases of CICS are compatible with the current release. The version of the DFHHPSVC module from the current release of CICS is compatible with earlier releases of CICS. The CSECT name (EPNAME) of the version of the DFHHPSVC module from earlier releases is IGC215 or IGCnnn, if SRBSVC=nnn was used as a CICS system generation parameter in the earlier release.
If you are not using the default SVC numbers, change the values 215 and 216 to the SVC numbers you have chosen.
Select the required IEASVCyy member by coding the SVC parameter (SVC=yy) in a SYS1.PARMLIB member (IEASYSxx), which you use to perform an IPL of your z/OS system. When you code new SVC numbers, they do not come into effect until you next perform an IPL of your z/OS system.

Installing the DFHCSVC module into the LPA

Use the following guidelines when you install the DFHCSVC module into the LPA:

Do not change DFHCSVC attributes.
Do not relink-edit the DFHCSVC module to install it into the LPA. The term install means move or copy a module into the LPA by using SMP/E, or a copying method that reblocks the copied modules when the target data set has a smaller block size than the data set you are copying from.
The DFHCSVC module, as supplied, has the attributes AMODE(31) and RMODE(ANY); do not change these attributes.

For further information about installing the DFHCSVC module in the LPA, see Installing CICS modules in the MVS link pack area.

Specifying the DFHCSVC number on the CICSSVC system initialization parameter

The current version of the CICS SVC module is compatible with all earlier releases of CICS, which enables you to run your earlier CICS regions with current regions in the same MVS image.

CICS contains a test to verify that it is using the correct level of the CICS DFHCSVC module. If CICS calls an SVC module using the SVC number specified on the CICSSVC system initialization parameter and that module is not at the current level, CICS issues message DFHKE0104. As a result of this message, CICS either abends with a system dump or prompts the operator to enter an alternative SVC number, depending on the option specified on the PARMERR system initialization parameter.