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CICS Terminal Control Table (TCT)

Master the CICS Terminal Control Table (TCT), the essential control table that manages terminal devices, user sessions, and terminal operations in CICS environments.

TCT Overview

The Terminal Control Table (TCT) is a critical CICS control table that contains entries for every terminal device that can be used within a CICS region. It defines terminal characteristics, device types, and session management.

Terminal Definitions

Each TCT entry defines a terminal's characteristics including device type, session parameters, and operational attributes.

  • Terminal ID and device information
  • Device type and capabilities
  • Session management options

Terminal Operations

TCT entries control how terminals are managed, how sessions are handled, and how terminal operations are performed.

  • Session establishment and termination
  • Security and authorization
  • Error handling and recovery

TCT Entry Structure

Each TCT entry contains detailed information about a terminal's characteristics, operational requirements, and runtime behavior within the CICS environment.

Terminal Identification

  • Terminal ID (4 characters)
  • Device name and type
  • Group assignment

Device Characteristics

  • Device type (3270, 5250, etc.)
  • Screen size and capabilities
  • Communication protocols

Session Attributes

  • Session timeout values
  • Security requirements
  • Error handling options

Terminal Types and Devices

CICS supports various terminal types and devices, each with specific characteristics and operational requirements.

3270 Terminals

Key Characteristics:

  • IBM 3270 Information Display System
  • Block-mode operation
  • 24x80 or 32x80 screen formats

Example TCT Entry:

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TERMINAL = T3270
DEVICE = 3270
STATUS = ENABLED
SECURITY = YES
TIMEOUT = 300
SCREENSIZE = 24X80

5250 Terminals

Key Characteristics:

  • IBM 5250 Information Display System
  • AS/400 and System/38 compatibility
  • Enhanced graphics capabilities

Example TCT Entry:

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TERMINAL = T5250
DEVICE = 5250
STATUS = ENABLED
SECURITY = YES
TIMEOUT = 300
SCREENSIZE = 24X80

Virtual Terminals

Key Characteristics:

  • Emulated terminal sessions
  • PC-based terminal emulation
  • Network-based connectivity

Example TCT Entry:

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TERMINAL = VIRTUAL
DEVICE = VTAM
STATUS = ENABLED
SECURITY = YES
TIMEOUT = 600
NETWORK = YES

Session Management

Understanding session management is crucial for terminal operations and user experience in CICS environments.

S

Session Establishment

Process:

Sign-on

Security:

Required

User authentication and session initialization with security validation.

A

Active Session

Status:

Active

Timeout:

Configurable

Ongoing session with transaction processing and user interaction.

T

Session Termination

Process:

Sign-off

Cleanup:

Automatic

Session cleanup and resource release upon user sign-off or timeout.

TCT Management

Learn how to manage TCT entries using CICS commands and understand the relationship between TCT and other CICS control tables.

TCT Commands

CEDA ADD TERMINAL:

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CEDA ADD TERMINAL(T3270) GROUP(TERMGRP)
DEVICE(3270)
STATUS(ENABLED)
SECURITY(YES)
TIMEOUT(300)
SCREENSIZE(24X80)

CEDA ALTER TERMINAL:

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CEDA ALTER TERMINAL(T3270) GROUP(TERMGRP)
TIMEOUT(600)
SECURITY(YES)

CEDA DELETE TERMINAL:

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CEDA DELETE TERMINAL(T3270) GROUP(TERMGRP)

TCT Relationships

Control Table Dependencies:

  • PCT: Transactions may reference TCT for terminal access
  • PPT: Programs may reference TCT for terminal operations
  • FCT: File access may be controlled by terminal

Terminal Operations:

  • Session establishment and termination
  • User authentication and authorization
  • Error handling and recovery

TCT Best Practices

Follow these best practices to optimize terminal operations, user experience, and system security.

Terminal Design

  • 1Use meaningful terminal IDs that reflect their purpose
  • 2Set appropriate timeout values based on usage patterns
  • 3Configure proper screen sizes for device types
  • 4Group related terminals together for efficient management

Security and Performance

  • 1Implement proper security controls for all terminals
  • 2Monitor terminal usage patterns and performance
  • 3Document terminal dependencies and relationships
  • 4Regularly review and update TCT entries

Quick Quiz

Question 1:

What is the primary purpose of the CICS Terminal Control Table (TCT)?

A) To store transaction definitions

B) To manage terminal devices and user sessions

C) To control file access permissions

D) To define program characteristics

Question 2:

Which terminal type is commonly used with IBM mainframes?

A) 5250

B) 3270

C) VT100

D) All of the above

Question 3:

What command is used to add a new terminal to the TCT?

A) CEDA ADD PROGRAM

B) CEDA ADD TRANSACTION

C) CEDA ADD FILE

D) CEDA ADD TERMINAL

Related Concepts

CICS Resource Definitions

Learn about CICS Resource Definition Online (RDO) and how TCT entries are managed.

CICS Architecture Overview

Understand how TCT fits into the overall CICS architecture and control table structure.