Defining links for use by the external CICS interface

This section describes how to define connections for use by non-CICS® programs using the external CICS interface (EXCI) to link to CICS server programs. The definitions required are similar to those needed for MRO links between CICS systems. Each connection requires a CONNECTION and a SESSIONS definition.

Because EXCI connections are used for processing work from external sources, you must not define any SEND sessions.

EXCI connections can be defined as "specific" or "generic". A specific EXCI connection is an MRO link on which all the RECEIVE sessions are dedicated to a single user (client program). A generic EXCI connection is an MRO link on which the RECEIVE sessions are shared by multiple users. Only one generic EXCI connection can be defined on each CICS region.

On definitions of both specific and generic connections, you must:

Figure 41 shows the definition of a specific EXCI connection.

Figure 41. Example definition for a specific EXCI connection. For use by a non-CICS client program using the external CICS interface.
DEFINE
  CONNECTION(EIP1)     local name for connection
  GROUP(groupname)     groupname of related definitions
  NETNAME(CLAP1)       user name on INITIALIZE_USER command
  ACCESSMETHOD(IRC)
  PROTOCOL(EXCI)
  CONNTYPE(Specific)   pipes dedicated to a single user
  INSERVICE(YES)
  ATTACHSEC(LOCAL)
DEFINE
  SESSIONS(csdname)    unique csd name
  GROUP(groupname)     same group as the connection
  CONNECTION(EIP1)     related connection
  PROTOCOL(EXCI)       external CICS interface
  RECEIVEPFX(<)
  RECEIVECOUNT(5)      5 receive sessions
  SENDPFX              leave blank
  SENDCOUNT            leave blank

For a specific connection, NETNAME must be coded with the name of the user program that will be passed on the EXCI INITIALIZE_USER command. CONNTYPE must be Specific.

Figure 42 shows the definition of a generic EXCI connection.

Figure 42. Example definition for a generic EXCI connection. For use by non-CICS client programs using the external CICS interface.
DEFINE
  CONNECTION(EIP2)     local name for connection
  GROUP(groupname)     groupname of related definitions
  ACCESSMETHOD(IRC)
  NETNAME()            must be blank for generic connection
  INSERVICE(YES)
  PROTOCOL(EXCI)
  CONNTYPE(Generic)    pipes shared by multiple users
  ATTACHSEC(LOCAL)
DEFINE
  SESSIONS(csdname)    unique csd name
  GROUP(groupname)     same group as the connection
  CONNECTION(EIP2)     related connection
  PROTOCOL(EXCI)       external CICS interface
  RECEIVEPFX(<)
  RECEIVECOUNT(5)      5 receive sessions
  SENDPFX              leave blank
  SENDCOUNT            leave blank

For a generic connection, NETNAME must be blank. CONNTYPE must be Generic.

Installing MRO and EXCI link definitions

You can install new MRO and EXCI connections dynamically, while CICS is fully operational--there is no need to close down interregion communication (IRC) to do so. Note that CICS commits the installation of connection definitions at the group level--if the install of any connection or terminal fails, CICS backs out the installation of all connections in the group. Therefore, when adding new connections to a CICS region with IRC open, ensure that the new connections are in a group of their own.

You cannot modify existing MRO (or EXCI) links while IRC is open. You should therefore ensure, when defining an MRO link, that you specify enough SEND and RECEIVE sessions to cater for the expected workload.

For further information about installing MRO links, see the CICS Resource Definition Guide.

Related concepts
Introduction to link definition
Multiregion operation
Installation considerations for multiregion operation
Related tasks
Identifying remote systems
Defining links for multiregion operation
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