SESSIONS resources

A SESSIONS resource defines the logical link between two CICS® systems that communicate using intersystem communication (ISC) or multiregion operation (MRO).

Before two systems can communicate using ISC or MRO, they must be logically linked through one or more sessions. The nature of the logical link determines how they can communicate. CICS does not use the SESSIONS name when the definition has been installed in the active system. This name is used only to identify the definition in the CSD file.

You use the CONNECTION attribute of the SESSIONS resource to name the CONNECTION with which these SESSIONS are associated when they are installed in the active systems.

Special considerations for different session types are:
MRO links and sessions
When you install a SESSIONS definition for MRO, you are telling CICS about a set of parallel sessions between this CICS and another CICS. The number of sessions is determined by the SENDCOUNT and RECEIVECOUNT attributes. The SEND sessions are identified by names created from the SENDPFX and SENDCOUNT attributes. The RECEIVE sessions are identified by names created from the RECEIVEPFX and RECEIVECOUNT attributes.
APPC (LUTYPE6.2) links and parallel sessions
When you install the SESSIONS definition, the sessions are grouped (for the benefit of z/OS® Communications Server) into a modeset, which is identified by the MODENAME. The individual sessions are named by a counter; the first session created is named -999, the second -998, and so on. The value of this counter is retained over a warm or emergency start. The number of sessions created is controlled by the MAXIMUM attribute on the SESSIONS definition.
LUTYPE6.1 CICS-CICS ISC links and sessions
The way in which the sessions are identified by CICS depends on the way you defined them, using SENDPFX, SENDCOUNT, RECEIVEPFX, and RECEIVECOUNT like MRO sessions, or using SESSNAME as for CICS-IMS sessions.
Note: Use APPC for all new CICS-CICS ISC links.
LUTYPE6.1 CICS-IMS links and sessions
When you install the SESSIONS definitions in the active CICS system, CICS identifies each session by the SESSNAME attribute.
INDIRECT connections
Because the association between an INDIRECT link and the intermediate systems used for communicating with it is made at installation time, install the definition for the intermediate system before the definition for the INDIRECT link. If you install the INDIRECT link first, it remains dormant until the intermediate definition is installed, and until any other already installed connections that make reference to it are resolved. For example, System A is indirectly connected with system C through system B. In system A, install the following definitions in this order:
  1. The intermediate system: 
    CONNECTION(B) NETNAME(B) ACCESSMETHOD(IRC) ...
  2. The INDIRECT link 
    CONNECTION(C) NETNAME(C) ACCESSMETHOD(INDIRECT)
   INDSYS(B) ...