RED Initialization for CICS

During CICS initialization as a part of the PLT, program SXX3STRT is executed. The program sets up the Mainframe RED environment in a CICS address space.

The SXXFINIT program is issued from SXX3ADMN once for the entire CICS address space and remains in effect until CICS termination. Therefore, the parameters and settings established for this call must be compatible with all the transactions that use RED operations and functions. All subsequent transactions execute using these initial SXXFINIT values, most of which can be overwritten by specific application usages. There is only one SXXFINIT and only one SXXFTERM call allowed for the entire CICS address space.

As a part of the Mainframe RED initialization in CICS, the following procedures occur:
  1. Program SXXACRM is loaded and made resident.
  2. Program SXXACNFG is loaded to determine Initialization Parameters and then released.
  3. Determine that a PCM is available for the LPAR in which the CICS region executes as specified in SXXACNFG.
  4. Enable and start a thin layered Resource Manager using Program SXXACRM.
  5. Issue a SXXFINIT call using the values present in SXXACNFG, and list the values on CICS JESLOG.
    When the initialization runs correctly, the following items are listed on CICS JESLOG: 
    SXX7700I RED for CICS - Starting Initialization          
SXX7701I RED for CICS - Initialized                      
XX8901I Mainframe RED Started 2016/04/11-11:34:16:734    
XX8911I Mainframe RED - V2.3.0.36 GA 04-10               
SXX7771I RED Monitor at - URL:TIBMON.<cics applname>            
SXX7705I RED Services - 2.3.0.30 04-11  Stg - Started    
SXX3700I Mainframe RED CICS Initialization complete
  6. The TCBs required for Mainframe RED internals are started in the CICS address space.
  7. As a part of SXX3STRT, specific Mainframe RED joins and connects are issued. These are used to handle SXCOTRED and SXXRTXN calls. All transactions linking to SXCOTRED use these JOIN and/or Connect definitions.
  8. Also part of SXX3STRT, a "shared" CICS GETMAIN is issued as an anchor control block with a z/OS token so it can be found by other transactions.
Besides issuing SXXFINIT, SXX3ADMN also sets up Resource Manager (TRUE) (the SXXACRM module ) for handling CICS RED API requests from user applications. These API requests are listed as follows:
  • SXXMJOIN and SXXMLEAV
  • SXXMRECM, SXXMRECP and SXXMFREE
  • SXXMSEND, SXXMSNDC and SXXMSNDR
Note: CICS transactions can never issue SXXFINIT, or SXXFTERM.

At CICS shutdown, SXX3COUT is executed as part of the shutdown PLT. This program terminates the CICS RED environment and removes the Resource Manager program. It also frees up the shared storage and z/OS token.

Functions of SXXACRM (TRUE) are to handle the following items:
  • Mainframe RED requests (for example, SXXMSEND, and SXXMRECM).
  • Mainframe RED SXXMJOIN and SXXLCONN and ensure that at transaction termination that the JOIN or CONNECT is terminated.
  • Commit processing.
  • Abend processing (Rollback).