The bridge facility

The 3270 user application was designed to be used with a real 3270 terminal and the CICS® commands that it uses assume that a real 3270 exists. The 3270 bridge mechanism simulates the presence of a real 3270 by providing internal interfaces for a virtual 3270, known as the bridge facility.

This replaces the terminal resource definition that you would normally provide for a 3270 application. The bridge facility emulates a real terminal in the following EXEC CICS interfaces:

You do not provide a resource definition for the bridge facility, but you can control some of the terminal properties used by providing a 3270 TERMINAL resource definition to be used as a template. The name of this TERMINAL definition, known as the facilitylike, is passed to the bridge on the Link3270 call.

See Defining the bridge facility for further information about the bridge facility.

Lifetime of the bridge facility

When simple transactions are run in single transaction mode, the bridge facility is created dynamically by CICS and deleted at the end of the transaction.

In session mode, multiple transactions or pseudotransactions can be run using the same bridge facility. In this mode the client application can request creation and deletion of the bridge facility, and can also specify a keeptime in BRIH-FACILITYKEEPTIME in the Allocate function. See Using Link3270 session mode.

The maximum keeptime value can be limited by the BRMAXKEEPTIME system initialization parameter. Bridge facilities are deleted automatically if they are inactive for the keeptime interval.

See the CICS System Definition Guide for information about the SIT.

Related concepts
The Link3270 bridge mechanism
Link3270 programming considerations
Related tasks
Defining the bridge facility
Using the Link3270 bridge
Writing the Link3270 client
Specifying system initialization parameters
Related reference
Link3270 message formats
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