Mainframe Interview Questions and Answers
Intermediate / 1 to 5 years experienced level questions & answers
Ques 1. 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 2. 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 3. 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 4. 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 5. 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 6. 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 7. 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 8. 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 9. 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 10. 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
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