Calling the Link3270 bridge

The Link3270 bridge supports the following external request mechanisms:

  1. EXEC CICS LINK. This includes both local link and DPL.
  2. The EXternal CICS® Interface (EXCI). This includes both the EXCI call interface and the EXEC CICS interface.
  3. The External Call Interface (ECI).

Calling Link3270 using LINK

The interface is the standard EXEC CICS LINK interface, for example:

 EXEC CICS LINK PROGRAM('DFHL3270') 		
           COMMAREA(Link3270_message) 		
           DATALENGTH(inbound_message_length)    
           LENGTH(outbound_message_length)

If you are using DPL:

The bridge header (BRIH) indicates whether the transaction ran successfully or not. See Link3270 diagnostics for a full description of the return codes from the Link3270 call.

See the CICS Application Programming Reference manual for a full description of the LINK command.

Calling Link3270 using EXCI

Either form of the EXCI interface can be used to run the bridge. The EXEC CICS interface is recommended for the single transaction mode. The call interface is recommended for the session mode. See Using the Link3270 bridge for a description of single transaction and session modes. See The EXCI programming interfaces. for information about using the EXCI interface.

Calling Link3270 using ECI

The interface is the standard ECI interface, passing the ECIPARMS parameter list. This should contain the following specific fields:

parameter value
eci_call_type synchronous or asynchronous
eci_program_name DFHL3270
eci_userid Userid for security validation. The user transaction runs with this userid
eci_password Password or Passticket for security validation
eci_tpn User transaction name
eci_commarea Address of the Link3270 message
eci_commarea_length Length of the Link3270 message

The other fields are set according to normal ECI programming. See CICS Family: Client/Server Programming for more information about the using the ECI interface.

The return code from the ECI call indicates whether the request was accepted by CICS. A return code of ECI_NO_ERROR does not imply that the transaction ran successfully. It implies that the transmission of the message was successful. The client application should look in the returned bridge header (BRIH) for the return code and abendcode. See Link3270 diagnostics for a full description of the return codes from the Link3270 call.

Multiple Router regions

If there are multiple router regions, all calls must be issued to the same region where the allocate-facility call was sent.

Related concepts
The Link3270 bridge mechanism
Link3270 programming considerations
Related tasks
Establish Link3270 suitability
Using the Link3270 bridge
Writing the Link3270 client
Using Link3270 messages
Using Link3270 single transaction mode
Using Link3270 session mode
Using data conversion with Link3270
Related reference
Link3270 message formats
Link3270 diagnostics
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