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The particulars of running a CICS transaction server

I want to run CICS transaction server(TS) 1.3 and CICS 4.1 on the same LPAR. For compatibility, can I run with the TS 1.3 SDFHLPA in the LPALIST and the type 6 SVC in the Nucleus? Will this cause any problems with CICS 4.1? Is there a recommended way to run the two in the same LPAR?

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The SVCs can be migrated without any problems. If you want to use the same SVC numbers, then install the CTS 1.3 ones and IPL. The out-of-service 4.1 will happily run with these newer SVCs. If you don't want to risk using the CTS 1.3 SVCs in the 4.1 region, then just use different numbers for the CTS 1.3 SVCs.

However, you cannot share LPA resident modules in this fashion. One of the regions must use LPA=NO and the other run with LPA=YES in the MVS image. I'd suggest running your existing 4.1 regions with LPA=NO for a day or two to determine the performance impact. Then, if this is acceptable, use LPA=YES in the (newer) CTS 1.3 region as this is where you will get the best benefit. Otherwise, use LPA=NO in the CTS 1.3 region and then only go to LPA=YES (with an IPL!) when all the 4.1 regions have gone away.

Robert Harris
CICS Technical Strategist -- CICS expert at

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This was first published in April 2003

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