CICS transaction routing

CICS® transaction routing allows terminals connected to one CICS system to run transactions in another CICS system.

Overview of transaction routing
CICS transaction routing allows terminals connected to one CICS system to run with transactions in another connected CICS system. You can distribute terminals and transactions around your CICS systems and still have the ability to run any transaction with any terminal.
Terminal-initiated transaction routing
When a request to start a transaction arrives at a CICS TOR, the TOR must find out on which system the transaction is to run. It does this by examining the installed transaction definition; in particular, the values of the DYNAMIC and REMOTESYSTEM options (see Defining transactions for transaction routing). Transaction routing can be either static or dynamic, depending upon the value of the DYNAMIC option.
Traditional routing of transactions started by ATI
You can use the traditional method of routing transactions that are started by automatic transaction initiation (ATI) for transactions where you cannot use the enhanced method.
Routing transactions invoked by START commands
To use the enhanced method of transaction routing for eligible terminal-related EXEC CICS START commands, the transaction must be defined as ROUTABLE(YES) in the requesting region (the region in which the START command is issued). The enhanced method of transaction routing supersedes the traditional method of transaction routing.
Allocation of remote APPC connections
A transaction running in the application-owning region can issue an ALLOCATE command, to obtain a session to an APPC terminal or connection that is owned by another system.
The relay program
When a terminal operator enters a transaction code for a transaction that is in a remote system, a transaction is attached in the TOR that executes a CICS-supplied program known as the relay program. This program provides the communication mechanism between the terminal and the remote transaction.
Basic mapping support (BMS)
The mapping operations of BMS are performed in the system on which the user's transaction is running; that is, in the application-owning region (AOR). The mapped information is routed between the terminal and this transaction through the relay transaction, as for terminal control operations.
Using the routing transaction, CRTE
The routing transaction, CRTE, is a CICS-supplied transaction used by a terminal operator to call transactions that are owned by a connected CICS system. CRTE facility is particularly useful for testing remote transactions before final installation.
System programming for transaction routing
You have to perform the following operations to implement transaction routing in your installation.

Parent topic: CICS intercommunication