Mainframe Interview Questions and Answers
Freshers / Beginner level questions & answers
Ques 1. Explain the purpose of COBOL in mainframes.
COBOL (Common Business Oriented Language) is a high-level programming language designed for business applications on mainframes.
Example:
COBOL code: MOVE 10 TO AMOUNT.
Ques 2. Explain the concept of partitioned datasets in mainframes.
Partitioned datasets (PDS) are file structures in mainframes that store data in separate members or partitions.
Example:
JCL for PDS: //DDNAME DD DSN=MY.PDS,DISP=SHR
Ques 3. What is the purpose of the IEBGENER utility in mainframes?
IEBGENER is a utility used for copying or generating datasets in mainframes.
Example:
IEBGENER JCL: //SYSIN DD * GENERATE MAXCC=0 /*
Ques 4. What is the purpose of the DD statement in JCL?
The DD (Data Definition) statement in JCL is used to define the input and output data files for a job step.
Example:
DD statement: //INPUT DD DSN=INPUT.FILE,DISP=SHR
Ques 5. What is the purpose of the IEFBR14 utility in mainframes?
IEFBR14 is a dummy utility used for job steps that do not require any processing, mainly for job control purposes.
Example:
IEFBR14 JCL: //STEP1 EXEC PGM=IEFBR14
Intermediate / 1 to 5 years experienced level questions & answers
Ques 6. What is a JCL (Job Control Language) in mainframes?
JCL is a scripting language used to define and execute job streams on mainframe systems.
Example:
JCL: //JOBNAME JOB ... //STEP1 EXEC PGM=PROGRAM1
Ques 7. What is VSAM (Virtual Storage Access Method) in mainframes?
VSAM is a file storage access method used in mainframes to organize and retrieve data efficiently.
Example:
VSAM definition: IDCAMS DEFINE CLUSTER ...
Ques 8. What is the purpose of DB2 in mainframes?
DB2 is a relational database management system (RDBMS) used in mainframes for storing and retrieving data.
Example:
SQL query: SELECT * FROM TABLE_NAME WHERE COLUMN = 'VALUE';
Ques 9. What is the purpose of IDCAMS utility in mainframes?
IDCAMS is a utility in mainframes used for defining and managing VSAM datasets.
Example:
IDCAMS command: IDCAMS DEFINE CLUSTER ...
Ques 10. Explain the function of the DFSORT utility in mainframes.
DFSORT is a utility used for sorting, merging, and copying datasets in mainframes.
Example:
DFSORT JCL: //SORTSTEP EXEC PGM=DFSORT...
Ques 11. Explain the concept of a CICS transaction in mainframes.
A CICS transaction is a logical unit of work initiated by a user request or a program in the CICS environment.
Example:
CICS transaction definition: EXEC CICS START TRANSID('XYZ')
Ques 12. Explain the function of the ISPF (Interactive System Productivity Facility) in mainframes.
ISPF is a software product for interactive application development and provides a menu-driven interface on mainframes.
Example:
ISPF command: TSO ISRDDN
Ques 13. What is the purpose of the GDG (Generation Data Group) in mainframes?
GDG is a feature in mainframes used for version control and management of sequential datasets.
Example:
GDG definition: //OUTPUT DD DSN=MY.DATA.GDG(+1),DISP=(NEW,CATLG)
Ques 14. Explain the purpose of the IDCAMS REPRO command in mainframes.
The IDCAMS REPRO command is used to copy data from one VSAM dataset to another in mainframes.
Example:
IDCAMS REPRO command: REPRO INFILE(IN_DATASET) OUTFILE(OUT_DATASET)
Ques 15. Explain the purpose of the JES (Job Entry Subsystem) in mainframes.
JES is a component in mainframes responsible for receiving, scheduling, and managing batch jobs.
Example:
JES command: //SYSOUT DD SYSOUT=A
Experienced / Expert level questions & answers
Ques 16. Explain the function of CICS (Customer Information Control System) in mainframes.
CICS is a transaction processing system that provides services for running applications concurrently on mainframes.
Example:
CICS command: EXEC CICS READ FILE(...)
Ques 17. Explain the concept of a mainframe 'region'.
A mainframe region is a logical partition where programs and data are executed and managed independently.
Example:
region definition in JCL: //REGION1 EXEC PGM=PROGRAM1,REGION=4M
Ques 18. Explain the concept of a REXX (Restructured Extended Executor) in mainframes.
REXX is a programming language used for scripting and automation in the mainframe environment.
Example:
REXX script: ADDRESS TSO 'SUBMIT JOBNAME'
Ques 19. What is the purpose of the IGGCSI00 utility in mainframes?
IGGCSI00 is a utility used for defining and managing the system catalog in a DB2 environment on mainframes.
Example:
IGGCSI00 JCL: //SYSIN DD * RUN PROGRAM(DSNTIAUL) PLAN(DSNTIUL1) ...
Ques 20. What is the function of the SYNCSORT utility in mainframes?
SYNCSORT is a utility used for sorting, merging, and copying datasets similar to DFSORT in mainframes.
Example:
SYNCSORT JCL: //SORTSTEP EXEC PGM=SYNCSORT ...
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