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Is TRANISO=YES and ISOLATE(NO) considered equivalent to TRANISO=NO in CICS TS?

Question & Answer


Question

If I turn on transaction isolation globally with TRANISO=YES, can I control which transaction it effects by turning on ISOLATE=YES on a transaction by transaction basis in CICS Transaction Server for z/OS (CICS TS)? This does not seem to be the case. By turning TRANISO on globally, it is effecting all transactions in my CICS region. Help me to understand this. I am expecting TRANISO=YES and ISOLATE(NO) to work the same as TRANISO=NO.

Answer

The answer is No. Using TRANISO=YES and ISOLATE(NO) should not be considered equivalent to TRANISO=NO. They do not mean the same thing.

With TRANISO=YES, a CICS transaction defined with ISOLATE(NO) will run in the shared subspace. It shares this subspace with other ISOLATE(NO) transactions. It does not run in basespace. If it runs off the end of a page of storage, the next page may not be allocated to the shared subspace; it might be owned by another subspace, or might be owned by basespace.

Another way to look at this is that with TRANISO=YES, there will be a number of isolated subspaces in the CICS address space, and therefore a higher proportion of the address space that even transactions defined with ISOLATE(NO) cannot access.

  • The CICS Resource Definition Guide has a good explanation of ISOLATE in the Transaction Attributes topic, under the description of ISOLATE.

  • Understand two transactions defined as ISOLATE(NO) can access to each others task lifetime storage, see Figure 2

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Product Synonym

CICS/TS CICSTS CICS TS CICS Transaction Server

Document Information

Modified date:
11 February 2016

UID

dwa1252196

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