Defining VTAM terminals

If your CICS® system is to communicate with terminals or other systems using VTAM® services, you must:

  1. Define CICS to ACF/VTAM with an APPL statement in SYS1.VTAMLST. For more information about defining an APPL statement for CICS, see the CICS Transaction Server for z/OS® Installation Guide.
  2. Define to VTAM the terminal resources that CICS is to use. For more information about defining terminal resources to VTAM, see Defining CICS terminal resources to VTAM.
  3. Define to CICS the terminal resources that it is to use. For more information about defining terminal resources to CICS, see Defining terminal resources to CICS.

Defining CICS terminal resources to VTAM

Each terminal, or each logical unit (LU) in the case of SNA terminals, that CICS is to use must be defined to VTAM. The terminals can be defined as local or remote.

Local VTAM terminals
can be SNA terminals connected to a channel-attached cluster controller, or they can be non-SNA 3270 terminals connected through a local control unit.
Remote VTAM terminals
are attached to an SNA cluster controller, which is connected through an SDLC line with a channel-attached communications controller. The communications controller may also be loaded with code to enable remote terminals to be connected to it by a binary synchronous (BSC) line.

You define terminals, controllers, and lines in VTAM tables 2 as nodes in the network. Each terminal, or each logical unit (LU) in the case of SNA terminals, must be defined in the VTAM tables with a VTAM node name that is unique throughout the VTAM domain.

If you are using VTAM 3.3 or later, you can define the AUTINSTMODEL name, printer, and alternate printer to VTAM by using VTAM MDLTAB and ASLTAB macros. These definitions are passed to CICS to select autoinstall models and printers.

For information about defining resources to VTAM, see the ACF/VTAM Installation and Resource Definition manual.

Defining terminal resources to CICS

A given VTAM terminal (or logical unit) may be defined explicitly in the CICS system definition file (CSD), in which case it has a TERMINAL name, and a NETNAME (which is the same as the VTAM node name). Terminals defined in this way have terminal entries installed at CICS startup.

If a terminal does not have an explicit definition in the CSD, CICS can create and install a definition dynamically for the terminal when it logs on, using the CICS autoinstall facility. CICS can autoinstall terminals by reference to TYPETERM and model TERMINAL definitions created with the AUTINSTMODEL and AUTINSTNAME attributes. For information about TYPETERM and TERMINAL definitions, see the CICS Resource Definition Guide.

If you use autoinstall, you must ensure that the CICS resource definitions correctly match the VTAM resource definitions. For programming information about VTAM logmode definitions and their matching CICS autoinstall model definitions, see the CICS Customization Guide.

If you specify the system initialization parameter TCTUALOC=ANY, CICS stores the terminal control table user area (TCTUA) for VTAM terminals above the 16MB line if possible. (See topic TACTUALOC for more information about the TCTUALOC parameter.)

Defining the terminal shutdown time limit

You can specify a time limit within which all VTAM terminals used by CICS must shut down, when CICS is shutting down. (This is to prevent a hung terminal stopping CICS shutting down.) You specify this time limit on the TCSWAIT system initialization parameter. You can also specify actions that CICS is to take, if the time limit is exceeded. You specify the actions on the TCSACTN system initialization parameter. More information about choosing appropriate values for TCSWAIT and TCSACTN is given in the following topics.

Choosing an appropriate value for TCSWAIT

The value that you specify on the TCSWAIT system initialization parameter should be large enough so that under normal circumstances all VTAM terminals and connections shutdown in an orderly fashion. To help choose this value, consider using a value slightly larger than the elapsed time between the following two CICS terminal control shutdown messages:

  DFHZC2305 Termination of VTAM sessions beginning
  DFHZC2316 VTAM ACB is closed
Note:
If you do not want a time limit (that is, you assume that all terminals never hang), specify the TCSWAIT=NO system initialization parameter.

Specifying that CICS is only to report hung terminals

To report hung terminals and not attempt to force-close them specify the TCSWAIT=mm (with an appropriate time interval) and TCSACTN=NONE system initialization parameters.

Specifying that CICS is to force close all hung terminals

To attempt to force-close all hung terminals specify the TCSWAIT=mm (with an appropriate time interval) and TCSACTN=UNBIND system initialization parameters.

Specifying that CICS is to force close some hung terminals

To attempt to force-close some hung terminals, and only report others, specify the TCSWAIT=mm (with an appropriate time interval) and TCSACTN=NONE system initialization parameters, and code a DFHZNEP routine that selects the required terminals and sets TWAOCN on for them.

Specifying that CICS is to force close the VTAM ACB

To attempt to force-close the CICS VTAM ACB if there are any hung terminals, specify the TCSWAIT=mm (with an appropriate time interval) and TCSACTN=FORCE system initialization parameters.

Limitations of the terminal shutdown time limit facility

The following limitations apply to the terminal shutdown time limit:


2.
VTAM has tables describing the network of terminals with which it communicates. VTAM uses these tables to manage the flow of data between CICS and the terminals.

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