What is the CICS CSD and why is it important?

The CSD (CICS System Definition) is a VSAM dataset that stores all CICS resource definitions — programs, transactions, files, mapsets, terminals, queues, and more. Before any resource can be used by a CICS application, it must be defined in the CSD and installed into the running CICS region. The CSD is managed with the CEDA transaction (online) or the DFHCSDUP batch utility (offline). Changes to the CSD take effect only after the resources are installed with CEDA INSTALL or EXEC CICS SET.

What is the difference between CEDA DEFINE and CEDA INSTALL?

CEDA DEFINE creates or modifies a resource definition in the CSD — it is a persistent change to the CSD dataset itself. CEDA INSTALL takes a definition from the CSD and loads it into the running CICS region's resource tables, making it available for use. You must do both: DEFINE to create/update the definition, then INSTALL to activate it. CEDA ALTER modifies an existing definition. CEDA DISCARD removes a resource from the CICS region at runtime (without deleting it from the CSD).

What does CEMT do in CICS and how is it different from CEDA?

CEMT (CICS Master Terminal) manages the runtime state of CICS resources — enabling/disabling programs, opening/closing files, setting transaction states, checking task status, and inquiring about system parameters. CEDA manages the CSD definitions (persistent). CEMT manages the live runtime state (temporary until next restart). For example, CEDA DEFINE creates a FILE definition; CEMT SET FILE(EMPFILE) OPEN opens it at runtime. CEMT changes are lost when CICS restarts unless the CSD definition also reflects the desired state.

How do I define and install a new CICS COBOL program?

Steps: (1) Compile the COBOL program and link-edit it into a load library in the CICS DFHRPL concatenation. (2) CEDA DEFINE PROGRAM(EMPINQ) GROUP(MYAPP) LANGUAGE(COBOL) RELOAD(NO). (3) CEDA DEFINE TRANSACTION(EMPI) GROUP(MYAPP) PROGRAM(EMPINQ). (4) CEDA INSTALL GROUP(MYAPP). The program is now available in CICS. When a user types EMPI at a terminal, CICS loads EMPINQ from the load library and executes it.

CICS Resource Definitions: CSD, CEDA, CEMT — Complete Administration Guide

Introduction: Resource Definitions — The Foundation of CICS Administration

Every resource that a CICS program uses — the program itself, the transaction that invokes it, the files it reads, the maps it displays — must be defined in CICS before it can be used. These definitions live in the CSD (CICS System Definition) dataset and are managed through the CEDA transaction (online) or the DFHCSDUP utility (batch). At runtime, the CEMT transaction manages the operational state of installed resources.

Understanding how to define, install, alter, and manage CICS resources is essential for CICS administrators and for developers who need to deploy their own programs into a CICS environment. This guide covers every major resource type with syntax examples and production best practices.

The CSD: CICS System Definition Dataset

The CSD is a VSAM KSDS dataset that stores CICS resource definitions. It is organised into Groups (logical containers for related definitions) and Lists (ordered sequences of groups that CICS processes at startup to install resources).

CSD Structure

text

CSD
├── GROUP: MYAPP
│   ├── PROGRAM: EMPINQ
│   ├── PROGRAM: EMPGET
│   ├── TRANSACTION: EMPI
│   ├── FILE: EMPFILE
│   └── MAPSET: EMPIMAPS
├── GROUP: MYDB2
│   ├── DB2CONN: CICSA2DB
│   └── DB2ENTRY: EMPIENTR
└── LIST: MYLIST
    ├── GROUP: MYAPP (position 10)
    └── GROUP: MYDB2 (position 20)

At CICS startup, the SIT (System Initialisation Table) specifies which Lists to process. CICS installs all groups in those lists in order.

CEDA: Online CSD Management

CEDA is the interactive CICS transaction for managing the CSD. All operations follow the pattern: CEDA verb RESOURCE(name) GROUP(grpname).

Defining a PROGRAM Resource

text

CEDA DEFINE PROGRAM(EMPINQ)
     GROUP(MYAPP)
     LANGUAGE(COBOL)
     EXECKEY(USER)           /* Run in user key (default) */
     RELOAD(NO)              /* Don't reload for each task */
     RESIDENT(NO)            /* Don't keep permanently in memory */
     STATUS(ENABLED)         /* Available for use */
     DESCRIPTION(Employee Inquiry Main Program)

Key PROGRAM options:

LANGUAGE: COBOL, ASSEMBLER, C, PL1
EXECKEY: USER (application programs) or CICS (system programs)
RELOAD(YES): Forces reload from load library on every invocation — useful in development, never in production (severe performance impact)
RESIDENT(YES): Keeps program in memory permanently — use for very frequently called programs

Defining a TRANSACTION Resource

text

CEDA DEFINE TRANSACTION(EMPI)
     GROUP(MYAPP)
     PROGRAM(EMPINQ)         /* Entry-point program */
     TWASIZE(0)              /* Transaction Work Area size */
     PROFILE(DFHCICST)       /* Transaction profile */
     STATUS(ENABLED)
     TASKDATALOC(ANY)        /* Task storage location */
     PRIORITY(1)             /* Dispatch priority (1-255) */
     DESCRIPTION(Employee Inquiry Transaction)

Defining a FILE Resource (VSAM KSDS)

text

CEDA DEFINE FILE(EMPFILE)
     GROUP(MYAPP)
     DSNAME(MYAPP.VSAM.EMPFILE)   /* VSAM dataset name */
     KEYLENGTH(6)                  /* KSDS key length */
     RECORDSIZE(43)                /* Fixed record length */
     ADD(YES)                      /* Allow WRITE */
     BROWSE(YES)                   /* Allow STARTBR/READNEXT */
     DELETE(YES)                   /* Allow DELETE */
     READ(YES)                     /* Allow READ */
     UPDATE(YES)                   /* Allow READ UPDATE/REWRITE */
     STATUS(ENABLED)
     OPENTIME(STARTUP)             /* Open at CICS startup */
     STRINGS(3)                    /* Concurrent access strings */

Defining a MAPSET Resource

text

CEDA DEFINE MAPSET(EMPIMAPS)
     GROUP(MYAPP)
     STATUS(ENABLED)
     RESIDENT(NO)
     DESCRIPTION(Employee Inquiry Screen Maps)

The MAPSET load module must be in the DFHRPL library concatenation in the CICS JCL.

CEDA INSTALL: Activating Definitions

After defining resources, install them into the running CICS region:

text

*── Install a single resource ────────────────────────────────────
CEDA INSTALL PROGRAM(EMPINQ) GROUP(MYAPP)

*── Install an entire group (all resources in the group) ─────────
CEDA INSTALL GROUP(MYAPP)

*── View a definition ────────────────────────────────────────────
CEDA VIEW PROGRAM(EMPINQ) GROUP(MYAPP)

*── Alter an existing definition (change RELOAD from YES to NO) ──
CEDA ALTER PROGRAM(EMPINQ) GROUP(MYAPP) RELOAD(NO)
CEDA INSTALL PROGRAM(EMPINQ) GROUP(MYAPP)

*── Delete a definition from the CSD ─────────────────────────────
CEDA DELETE PROGRAM(EMPINQ) GROUP(MYAPP)

DFHCSDUP: Batch CSD Management

DFHCSDUP is the batch utility for CSD operations — essential for migration, backup, and mass updates. Run it as a batch job:

jcl

//CSDUP    EXEC PGM=DFHCSDUP
//STEPLIB  DD DSN=CICSTS56.CICS.SDFHLOAD,DISP=SHR
//DFHCSD   DD DSN=CICSTS56.CICS.DFHCSD,DISP=SHR
//SYSPRINT DD SYSOUT=*
//SYSIN    DD *
  LIST ALL INTO(MYAPP.CSD.LISTING)
  COPY GROUP(MYAPP) TO(MYAPP.TEST.CSD)
  MIGRATE CSD(MYAPP.OLD.CSD)
/*

Common DFHCSDUP operations:

LIST ALL: Document all CSD definitions (produces a report)
COPY GROUP(name) TO(target-csd): Copy a group to another CSD (e.g., from test to production)
EXTRACT: Generate CEDA commands that reproduce a definition (useful for documentation and migration)
MIGRATE: Migrate definitions from an older CICS CSD format

CEMT: Runtime Resource Management

CEMT (CICS Master Terminal) manages the operational state of installed resources. Unlike CEDA (which changes the CSD), CEMT changes the live CICS region and are not persistent across CICS restarts.

File Operations

text

*── Open a file that was closed ─────────────────────────────────
CEMT SET FILE(EMPFILE) OPEN

*── Close a file for maintenance (e.g., before VSAM REORG) ──────
CEMT SET FILE(EMPFILE) CLOSED

*── Make a file read-only (prevent updates) ──────────────────────
CEMT SET FILE(EMPFILE) READONLY

*── Re-enable a disabled file ────────────────────────────────────
CEMT SET FILE(EMPFILE) ENABLED

*── Inquire on file status ───────────────────────────────────────
CEMT INQUIRE FILE(EMPFILE)

Program Operations

text

*── Disable a program (stop new uses, existing tasks continue) ───
CEMT SET PROGRAM(EMPINQ) DISABLED

*── Re-enable it ─────────────────────────────────────────────────
CEMT SET PROGRAM(EMPINQ) ENABLED

*── Force CICS to reload the program next time it is needed ──────
CICS SET PROGRAM(EMPINQ) NEWCOPY

NEWCOPY is the most frequently used CEMT command during development — it forces CICS to load a fresh copy of the program from the load library, picking up recent compilations without cycling the CICS region.

Transaction Operations

text

*── Disable a transaction (new starts rejected) ──────────────────
CEMT SET TRANSACTION(EMPI) DISABLED

*── Re-enable ────────────────────────────────────────────────────
CEMT SET TRANSACTION(EMPI) ENABLED

Task Management

text

*── List all running tasks ───────────────────────────────────────
CEMT INQUIRE TASK ALL

*── Cancel a specific task by task number ────────────────────────
CEMT SET TASK(00037) PURGE

*── Force cancel (use when PURGE doesn't work) ───────────────────
CEMT SET TASK(00037) FORCEPURGE

EXEC CICS SET: Programmatic Resource Management

CICS resources can also be managed programmatically from COBOL programs using EXEC CICS SET commands — useful for automated operations and self-healing applications:

cobol

*── Open a file programmatically ─────────────────────────────────
EXEC CICS SET FILE('EMPFILE')
              OPEN
              RESP(WS-RESP)
END-EXEC.

*── Force NEWCOPY on a program ───────────────────────────────────
EXEC CICS SET PROGRAM('EMPINQ')
              NEWCOPY
              RESP(WS-RESP)
END-EXEC.

*── Disable a transaction ────────────────────────────────────────
EXEC CICS SET TRANSACTION('EMPI')
              STATUS(DISABLED)
              RESP(WS-RESP)
END-EXEC.

CSD Group and List Management

Organising definitions into groups and lists is a discipline that prevents CSD sprawl:

text

*── Add a group to a list (done once when creating new application) ─
CEDA ADD GROUP(MYAPP) LIST(MYLIST)

*── Remove a group from a list ───────────────────────────────────
CEDA REMOVE GROUP(MYAPP) LIST(MYLIST)

*── View all groups in a list ────────────────────────────────────
CEDA VIEW LIST(MYLIST)

Best practices for CSD organisation:

One group per application subsystem (EMPGRP, ORDGRP, INVGRP)
Separate groups for shared infrastructure (DBCONN, WEBSVCS, COMMON)
One list per CICS region SIT startup (PRODLIST for production, TESTLIST for test)
Never mix test and production definitions in the same group
Use DFHCSDUP EXTRACT regularly to document CSD contents in source control

Key Takeaways

CICS resource definitions are the administrative foundation of every CICS application. CEDA manages the persistent CSD — DEFINE to create, ALTER to modify, INSTALL to activate, DELETE to remove. CEMT manages the runtime state — OPEN/CLOSE files, ENABLE/DISABLE programs and transactions, NEWCOPY to pick up recompiled programs, PURGE to cancel runaway tasks. DFHCSDUP provides batch CSD management for production migrations and documentation. Mastering these tools allows you to deploy, manage, and troubleshoot CICS applications confidently in any mainframe environment.

For understanding how to monitor CICS performance and diagnose problems in production, continue with CICS Monitoring and Performance. For the complete CICS course, visit the CICS Mastery Course.