INDEXED BY creates an index for efficient table processing.

Example:

05 EMP-NAME PIC X(20)
   OCCURS 100 TIMES
   INDEXED BY EMP-IDX.

CALL transfers control from one program to another.

Example:

CALL 'SUBPROG'

LINKAGE SECTION is used to receive data from the calling program.

The Linkage Section is used for communication between programs.

Example:

LINKAGE SECTION.
01 LK-CUSTOMER-ID PIC X(10).

Static CALL (program name is fixed):

CALL 'PAYROLL'

Dynamic CALL (program name is determined at runtime):

CALL WS-PROGRAM-NAME

EVALUATE works like a CASE statement.

Example:

EVALUATE WS-GRADE
   WHEN 'A'
      DISPLAY 'EXCELLENT'
   WHEN 'B'
      DISPLAY 'GOOD'
   WHEN OTHER
      DISPLAY 'AVERAGE'
END-EVALUATE

CONTINUE does nothing and passes control to the next statement.

NEXT SENTENCE transfers control to the next period (.).

In modern COBOL, CONTINUE is generally preferred.

SSRANGE is a compiler option used to detect array index errors during execution.

Benefits: Prevents table overflow and helps debugging.

Inline PERFORM executes statements without creating a separate paragraph.

Example:

PERFORM
   ADD 1 TO WS-COUNT
   DISPLAY WS-COUNT
END-PERFORM

Examples: Salary processing → Batch, ATM withdrawal → Online CICS program.

CALL BY REFERENCE: The called program receives the actual memory address.

CALL 'SUBPROG' USING WS-AMOUNT

Changes made in the subprogram affect the calling program.

CALL BY CONTENT: The called program receives a copy of the data.

CALL 'SUBPROG' USING BY CONTENT WS-AMOUNT

Changes made in the subprogram do not affect the original data.

The INITIAL clause causes Working-Storage items to be initialized whenever the program is called.

Example:

PROGRAM-ID. TESTPROG IS INITIAL.

Benefit: Ensures fresh data values for each execution.

Examples:

Subscript:

MOVE EMP-NAME(5) TO WS-NAME

Index:

SET EMP-IDX TO 5

SEARCH ALL performs a binary search on a table.

Requirements:

• Table must be sorted
• OCCURS clause with INDEXED BY

Example:

SEARCH ALL EMP-TABLE
   WHEN EMP-ID(EMP-IDX) = WS-ID
      DISPLAY 'FOUND'
END-SEARCH

Benefits: Faster than SEARCH, efficient for large tables.

INSPECT is used to count, replace, or convert characters within a string.

Example (Count):

INSPECT WS-NAME
   TALLYING WS-COUNT
   FOR ALL 'A'

Example (Replace):

INSPECT WS-NAME
   REPLACING ALL 'A' BY 'X'

STRING combines multiple fields into one field.

Example:

STRING WS-FIRST-NAME
       SPACE
       WS-LAST-NAME
INTO WS-FULL-NAME
END-STRING

Output: PUNIT KUMAR

UNSTRING splits a string into multiple fields.

Example:

UNSTRING WS-NAME
   DELIMITED BY SPACE
   INTO WS-FIRST-NAME
        WS-LAST-NAME
END-UNSTRING

Input: PUNIT KUMAR → Output: PUNIT / KUMAR

Reference Modification allows accessing part of a field.

Syntax: field(start:length)

Example:

MOVE WS-NAME(1:5) TO WS-FIRST

If WS-NAME = 'PUNITKUMAR' then WS-FIRST = 'PUNIT'.

SYNC aligns data items on natural machine boundaries to improve performance.

Example:

01 WS-COUNT PIC S9(4) COMP SYNC.

Benefits: Faster processing and better hardware alignment.

CONTINUE is a no-operation statement that passes control to the next statement.

IF WS-FLAG = 'Y'
   CONTINUE
END-IF

EXIT is used to exit a paragraph or indicate the end of a section.

EXIT.

Difference:

DISP defines dataset status and what happens after job completion.

Syntax: DISP=(status,normal-action,abnormal-action)

Example: DISP=(NEW,CATLG,DELETE)

Meaning: NEW → Create dataset, CATLG → Catalog if job succeeds, DELETE → Delete if job fails.

Example: DISP=SHR

GDG (Generation Data Group) is a collection of related datasets with automatic version management.

MY.FILE.GDG(+1)
MY.FILE.GDG(0)
MY.FILE.GDG(-1)

+1 = New generation, 0 = Current generation, -1 = Previous generation.

PROC is a reusable set of JCL statements.

Example:

//MYPROC PROC
//STEP1 EXEC PGM=SORT
//PEND

Usage: //JOB1 EXEC MYPROC

Benefits: Reusability, reduced coding effort.

COND controls execution of steps based on previous return codes.

Example: COND=(4,LT)

Meaning: Skip current step if previous return code is less than 4.

A return code indicates job execution status.

REGION specifies memory allocation for a job or step.

Example: REGION=0M

Meaning: Use all available memory.

A temporary dataset exists only during job execution.

Example: DSN=&&TEMPFILE

Characteristics: Not cataloged, deleted automatically after job completion.

Symbolic parameters allow dynamic values in procedures.

Example:

//MYPROC PROC PGMNAME=COBPROG
//STEP1 EXEC PGM=&PGMNAME

Usage: //EXECPROC EXEC MYPROC,PGMNAME=TESTPROG

Used to restart a failed job from a specific step.

Example: RESTART=STEP3

Benefit: Avoids rerunning completed steps.

IEBGENER is used to copy sequential datasets.

Example: //STEP1 EXEC PGM=IEBGENER

Uses: Dataset copy, backup creation, printing.

IEBCOPY copies partitioned datasets (PDS).

Example: //STEP1 EXEC PGM=IEBCOPY

Uses: Copy PDS members, compress PDS.

SORT is used to sort datasets.

Example: //STEP1 EXEC PGM=SORT

Sort control: SORT FIELDS=(1,10,CH,A)

Meaning: Sort first 10 characters in ascending order.

IDCAMS is used for VSAM dataset operations.

Example: //STEP1 EXEC PGM=IDCAMS

Common commands: DEFINE, DELETE.

IEFBR14 is a “do-nothing” IBM utility (it simply ends with RC=0). It’s commonly used to create or delete datasets via DD statements and DISP.

Example (create):

//STEP1 EXEC PGM=IEFBR14
//OUTDD DD DSN=MY.DATASET,DISP=(NEW,CATLG,DELETE),
//         SPACE=(TRK,(5,2)),UNIT=SYSDA

PARM passes parameters from JCL to the program (via the EXEC statement).

Example:

//STEP1 EXEC PGM=MYPROG,PARM='MODE=TEST,DATE=20260616'

The program reads the value from its runtime parameter area.

DD DUMMY tells the program there is no real input/output dataset (treated as empty input or discarded output).

DD * is used for in-stream data (data provided directly inside the JCL).

Examples:

//INP  DD DUMMY
//SYSIN DD *
  SORT FIELDS=(1,10,CH,A)
/*

SYSIN is typically used to provide control statements/input parameters to utilities (like SORT, IDCAMS, etc.).

SYSPRINT is typically used to capture reports/messages/output listings produced by utilities.

A Tablespace is a physical storage structure that contains one or more tables.

Benefits: Organizes data storage, improves performance, simplifies space management.

Example:

CREATE TABLESPACE TS_EMP
IN DB_EMP;

An Index is a database object used to speed up data retrieval.

Example:

CREATE INDEX IX_EMP_ID
ON EMPLOYEE(EMP_ID);

Benefits: Faster SELECT queries, reduced table scans.

A Clustered Index determines the physical order of rows in a table.

Example:

CREATE UNIQUE INDEX IX_EMP
ON EMPLOYEE(EMP_ID)
CLUSTER;

Benefits: Faster range scans, improved sequential access.

A Cursor is used to process query results one row at a time.

Steps: DECLARE → OPEN → FETCH → CLOSE

Example:

DECLARE C1 CURSOR FOR
SELECT EMP_ID, EMP_NAME
FROM EMPLOYEE;

Example:

SELECT EMP_NAME
INTO :HV-NAME
FROM EMPLOYEE
WHERE EMP_ID = 100;

A Package contains executable SQL statements generated during the bind process.

Benefits: Better performance, SQL execution control, security management.

A Plan is an executable structure that references one or more packages.

Relationship: Application Program → Package → Plan

BIND creates a package or plan from SQL statements.

Example: BIND PACKAGE(...)

Benefits: Optimizes SQL, creates access paths.

REBIND regenerates access paths without recompiling the program.

Example: REBIND PACKAGE(PKGNAME)

When used: Statistics changed, performance tuning required.

RUNSTATS collects table and index statistics.

Example: RUNSTATS TABLESPACE DB1.TS1

Benefits: Better optimizer decisions, improved query performance.

EXPLAIN shows how DB2 will execute an SQL statement.

Example:

EXPLAIN PLAN FOR
SELECT * FROM EMPLOYEE;

Uses: Performance analysis, query tuning.

A Primary Key uniquely identifies each row in a table.

Example:

CREATE TABLE EMPLOYEE
(
 EMP_ID INTEGER PRIMARY KEY,
 EMP_NAME VARCHAR(50)
);

Rules: Unique, cannot be NULL.

A Foreign Key establishes a relationship between tables.

Example:

ALTER TABLE ORDERS
ADD CONSTRAINT FK_CUST
FOREIGN KEY (CUST_ID)
REFERENCES CUSTOMER(CUST_ID);

Referential Integrity ensures consistency between parent and child tables.

Benefits: Prevents orphan records, maintains data accuracy.

Example: NAME CHAR(20), CITY VARCHAR(50)

SQLCODE indicates the result of SQL execution.

Example:

IF SQLCODE = 0
   DISPLAY 'SUCCESS'
END-IF

A Deadlock occurs when two transactions wait indefinitely for resources locked by each other.

Example:

• Transaction A → waits for Row B
• Transaction B → waits for Row A

Result: DB2 rolls back one transaction (often SQLCODE -911 or -913).

A View is a virtual table based on one or more tables.

Example:

CREATE VIEW EMP_VIEW AS
SELECT EMP_ID,
       EMP_NAME
FROM EMPLOYEE;

Benefits: Security, simplified queries, data abstraction.

Examples:

DELETE FROM EMPLOYEE
WHERE EMP_ID = 100;

TRUNCATE TABLE EMPLOYEE;

DROP TABLE EMPLOYEE;

COMMAREA (Communication Area) is used to pass data between two CICS programs.

Example:

EXEC CICS LINK
     PROGRAM('PROG2')
     COMMAREA(WS-COMMAREA)
     LENGTH(100)
END-EXEC

Benefits: Program-to-program communication, temporary data transfer, fast and efficient.

The maximum size of a COMMAREA is 64 KB (65,535 bytes).

For larger data transfers, IBM recommends using Channels and Containers.

Example:

EXEC CICS LINK PROGRAM('PROG2') END-EXEC
EXEC CICS XCTL PROGRAM('PROG2') END-EXEC

Channels and Containers are modern alternatives to COMMAREA.

• Channel: collection of containers
• Container: holds application data

Advantages: Can hold large data, easier management, recommended for modern CICS applications.

EIB (Execute Interface Block) is a control block automatically provided by CICS.

It contains transaction ID, task information, response codes, and terminal information.

Example:

IF EIBCALEN > 0
   DISPLAY 'DATA RECEIVED'
END-IF

EIBCALEN contains the length of data passed through COMMAREA.

Example:

IF EIBCALEN = 0
   DISPLAY 'FIRST TIME ENTRY'
END-IF

Usage: detect initial invocation, validate incoming COMMAREA.

HANDLE ABEND is used to handle abnormal program termination.

Example:

EXEC CICS HANDLE ABEND
     LABEL(ABEND-ROUTINE)
END-EXEC

Benefits: prevents transaction failure, enables custom error handling.

HANDLE CONDITION intercepts specific CICS exceptions.

Example:

EXEC CICS HANDLE CONDITION
     NOTFND(NOT-FOUND-PARA)
END-EXEC

If a record is not found, control goes to NOT-FOUND-PARA.

RESP is the primary response code and RESP2 provides detailed error information.

Example:

EXEC CICS READ
     FILE('CUSTFILE')
     INTO(WS-REC)
     RESP(WS-RESP)
     RESP2(WS-RESP2)
END-EXEC

Example:

EXEC CICS READ
     FILE('CUSTFILE')
     NOHANDLE
END-EXEC

TSQ (Temporary Storage Queue) is a queue used for temporary data storage.

• Records can be read randomly
• Data survives task termination

Example:

EXEC CICS WRITEQ TS
     QUEUE('TEMPQ')
     FROM(WS-DATA)
END-EXEC

TDQ (Transient Data Queue) is used for sequential processing of temporary data.

Types: Intra-partition TDQ, Extra-partition TDQ

Example:

EXEC CICS WRITEQ TD
     QUEUE('PRINTQ')
     FROM(WS-DATA)
END-EXEC

BMS (Basic Mapping Support) is used to design CICS screens.

Components: Physical Map, Symbolic Map

Benefits: Screen formatting, user interaction, input validation.

SEND MAP displays the screen to the user.

Example:

EXEC CICS SEND MAP('CUSTMAP')
END-EXEC

RECEIVE MAP receives user input from the screen.

Example:

EXEC CICS RECEIVE MAP('CUSTMAP')
END-EXEC

MDT (Modified Data Tag) indicates whether a field has been modified.

Benefits: Reduces network traffic and improves performance.

PCT (Program Control Table) maps transaction IDs to programs.

Example:

Transaction: CUST → Program: CUSTPGM. When the user enters CUST, CICS executes CUSTPGM.

PPT (Processing Program Table) contains program definitions.

It stores details like program name, language, load information, and execution attributes.

A pseudo-conversational program ends after each user interaction and restarts when the user responds.

Typical flow:

• SEND MAP
• RETURN TRANSID
• User enters data
• Transaction restarts
• RECEIVE MAP

Benefits: Saves memory, improves scalability, and is a standard design in modern CICS applications.

A Linear Data Set (LDS) is a VSAM dataset that does not contain records or keys. Data is stored as a sequence of bytes.

Characteristics: No record definition, no key fields, often used by DB2 for tablespaces and indexes.

Example:

DEFINE CLUSTER(NAME(DB2.LDS)
LINEAR)

A Key Range represents the lowest and highest key values stored in a KSDS dataset.

Example: Lowest Key: 1000, Highest Key: 9999

Benefits: Faster searches, efficient index navigation, improved performance during sequential processing.

No. The primary key of a KSDS record cannot be updated directly.

To change a key:

• Read the record
• Delete the existing record
• Insert a new record with the new key

Reason: The key determines the physical and logical location of the record.

Dynamic Access allows an application to switch between sequential and random processing during execution.

Example: ACCESS MODE IS DYNAMIC

Benefits: Flexibility, better performance, useful in online applications.

By defining free space during dataset creation.

Example: FREESPACE(20 10)

Meaning: 20% free space in CI, 10% free space in CA. Benefits: Fewer splits, better performance.

Free Space is reserved empty space within a KSDS dataset to accommodate future inserts.

Example: FREESPACE(15 5)

Advantages: Reduces CI splits and improves insert performance.

An Alternate Index provides an alternate access path to a KSDS dataset.

Example: Primary Key: EMP_ID, Alternate Key: EMP_NAME

Benefits: Multiple search methods and faster retrieval.

A PATH connects an Alternate Index to its base cluster. Without PATH, applications cannot use the Alternate Index.

Structure: KSDS → AIX → PATH

UPGRADESET automatically updates the Alternate Index whenever the base cluster changes.

Example:

DEFINE ALTERNATEINDEX
UPGRADE

Benefit: Keeps AIX synchronized.

VERIFY synchronizes catalog information with the actual dataset.

Example: VERIFY FILE(MY.KSDS)

Used after: System failures, incomplete updates.

REPRO is used to copy VSAM and non-VSAM datasets.

Example:

REPRO -
INFILE(INPUT) -
OUTFILE(OUTPUT)

Uses: Data migration, backup, dataset loading.

EXPORT creates a backup of a VSAM cluster.

EXPORT -
OBJECTS(MY.KSDS)

IMPORT restores a previously exported cluster.

IMPORT -
INFILE(BACKUP)

LISTCAT displays information about VSAM datasets.

Example: LISTCAT ENT(MY.KSDS) ALL

Shows: CI size, CA size, record length, free space, and more.

RBA (Relative Byte Address) identifies the physical location of a record in an ESDS dataset.

Example:

• Record A → RBA 000000
• Record B → RBA 000120

It is used for direct access in ESDS.

A Cluster is the complete VSAM dataset definition.

Contains: Data component, Index component (KSDS only).

Example:

DEFINE CLUSTER(NAME(CUST.KSDS))

Share Options determine dataset accessibility.

Example: SHAREOPTIONS(2 3)

Controls: Cross-region sharing, cross-system sharing.

Benefits: Multi-user access.

After an abnormal shutdown, catalog information may not match the actual dataset.

VERIFY: Corrects catalog inconsistencies and makes the dataset available again.

Example:

VERIFY FILE(CUST.KSDS)

Example:

DELETE CUST.KSDS CLUSTER