Upgrading MRO

This topic tells you about the changes that you need to make to MRO connections when you migrate from one release of CICS® to another. This information applies to all currently supported CICS TS releases, regardless of your current release and the target release.

These steps assume that RACF® is your external security manager (ESM).

If you are upgrading from an end-of-service release, you might need to take additional actions that are relevant to your current, end-of-service release, along with the actions summarized in the upgrade instructions provided below. For details, see Upgrading from end-of-service releases.

Upgrade actions

Table 1 lists the actions you must perform when upgrading to a higher CICS release, regardless of your current release and the target release. The sections that describe these actions in detail are tagged with

Table 2 lists the actions that depend on your current release and your target release. The sections that describe version-dependent actions in detail also lay out the applicable current-target pairs.

Table 1. Common actions
Action Mandatory or optional?
Install and test DFHCSVC Mandatory
Install and test DFHIRP Mandatory
Define DFHAPPL.applid profiles in the RACF FACILITY class Optional
Test MRO Optional
Table 2. Version-dependent actions
Your current version Your target version Action Mandatory or optional?
5.5 or earlier 5.6 or later Evaluate your use of COMMAREAs used for DPL requests over MRO connections Mandatory, if you have a mixed environment

Install and test DFHCSVC

All versions

Install the CICS SVC routine, DFHCSVC, in the LPA, and specify a new CICS SVC number for this routine in the MVS™ SVCPARM table. Co-existence is not recommended or necessary: DFHCSVC is compatible with earlier releases and the latest CICS TS version supports all the earlier releases of CICS. If, however, the new DFHCSVC must coexist with an older version, rename one of them so that both versions can be installed in the LPA. Test the new SVC on stand-alone CICS regions, without using any MRO. You can do this running the CICS IVP, DFHIVPOL.

Find information about installing DFHCSVC here: Installing CICS modules in the MVS link pack area.

Install and test DFHIRP

All versions

For MRO, the interregion communication program DFHIRP is installed in the link pack area (LPA). The CICS TS for z/OS®, Version 6.1 DFHIRP module is compatible with earlier releases, and works with all releases of CICS. DFHIRP can be used only from the LPA. So, in a z/OS image you can have only one version of the module that is named DFHIRP and this version must be at the highest release level of the CICS regions that run in that z/OS image.

In a Parallel Sysplex®, where MRO communication between MVS images is through XCF/MRO, the DFHIRP programs that are installed in the different MVS images can be at different release levels. However, the DFHIRP in an MVS image must still be installed from the highest release of CICS running in that MVS image. For example, a CICS TS 5.5 DFHIRP can communicate with a CICS TS for z/OS, Version 6.1 DFHIRP across XCF/MRO, but the CICS regions that run in the MVS with the CICS TS 5.5 DFHIRP cannot be later than CICS TS 5.5.

Install the CICS interregion communication program, DFHIRP, in a suitable LPA library. If your strategy is to quiesce all users of DFHIRP on the z/OS image that is being upgraded, you can use the dynamic LPA function to replace DFHIRP. To update DFHIRP dynamically, perform the steps below. If you do not follow these steps, you must IPL MVS with the CLPA option. Failing to shut down all users of DFHIRP during the upgrade process can cause incompatibility between control blocks and result in abends.

  1. Quiesce all users of DFHIRP. For example, WebSphere® EXCI, CTG EXCI, all CICS regions, including any CMASs, must either be shutdown or logged off from MRO/XM. All other work that uses EXCI must be shut down.
    Important: The process described here does not include upgrading CICSPlex® SM to the CICS TS 6.1 level. For more information, see All versions Upgrade a maintenance point CMAS.
  2. Update LPA modules DFHCSVC, DFHDSPEX, DFHDUMPX, DFHIRP, DFHSSEN and DFH99SVC with the dynamic LPA facility. Specify the ADD verb.
  3. Run the CICS TS 6.1 supplied utility DFHCSVCU to update the z/OS SVC table as documented in Running the DFHCSVCJ job .
  4. Restart MRO by either setting IRC connected in all running CICS regions or restarting the CICS regions.
  5. Dynamic changes are discarded by an IPL, so you must schedule an IPL for a convenient time to ensure that all dynamically-applied changes are correctly applied to the z/OS system libraries.

Test your production MRO CICS regions, under your existing release of CICS, but use the new SVC number and the new DFHIRP. For this test, run without any logon or bind-time security checking: that is, do not define any RACF FACILITY class profiles.

Define DFHAPPL.applid profiles in the RACF FACILITY class

All versions

You can define the DFHAPPL.applid profiles in the RACF FACILITY general resource class to control access to the CICS APPLID. When the profiles are ready for all the MRO regions, test the production regions again with the new SVC and DFHIRP, this time use the FACILITY class profiles for logon and bind-time security checking.

Any CICS region without a specific DFHAPPL.applid profile, or applicable generic profile, permits all logon and connect requests. For more information, see MRO connection (bind-time) security.

Evaluate your use of COMMAREAs used for DPL requests over MRO connections

This action depends on your current release and your target release.
  • Your current release: 5.5 or earlier
  • Your target release: 5.6 or later
As of CICS TS 5.6, COMMAREAs greater than 24 KB are supported for DPL requests over MRO connections. However, the use of COMMAREAs that is larger than 24 KB for DPL requests over MRO connections requires that both regions are at Version 5.6 or later. At Version 5.6 and higher, a COMMAREA that is greater than 24KB is shipped using the DFHTRANSACTION channel. Complication might arise if you have a mixed environment that has regions at Version 5.6 or later as well as regions at Version 5.5 or earlier. Issues might occur when passing a COMMAREA larger than 24 KB; if the target region is at Version 5.5 or earlier, an abend (for example, AXGE) will occur. In this case, you can disable the capability by specifying the following feature toggle:
com.ibm.cics.dpl.32kcommarea=false

The feature toggle means that the COMMAREAs used for DPL requests over MRO connections must not exceed 24 KB, as in CICS TS 5.5 or earlier.

Important: When all regions in your environment are at Version 5.6 or later, you should remove this feature toggle or re-enable the capability by specifying com.ibm.cics.dpl.32kcommarea=true.

Test MRO

All versions

If the production MRO regions successfully log on to the new IRP with the new SVC, and bind-time security checking works successfully, use the new DFHIRP and SVC for the production regions. When the production regions run successfully under the CICS SVC and IRP, you can initialize and test some CICS TS regions with MRO. These test regions can coexist in the same z/OS image as the production regions, all using the same SVC and IRP.