Mainframe Interview Questions
Collected from real-time interviews by Venkat since2010
YouTube Channel: Venkat since2010
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COBOL Questions
- What are the different ways to pass data between Cobol-to-Cobol programs?
- Difference between subscript and index.
- Explain scope terminators.
- How will you handle variable length records in COBOL?
- Difference between COMP and COMP-3.
- What is SSRANGE and NOSSRANGE?
- What happens if STOP RUN is used in subprogram?
- How to compare two files in COBOL?
- Explain file matching logic.
- How to read a file in reverse order?
- How to delete duplicate records in COBOL?
- How to write alternate records to output file?
- How to abend a program manually?
- How to handle empty files in COBOL?
- Difference between static and dynamic calls.
- What are level 77 variables?
- Explain OCCURS clause.
- Difference between SEARCH and SEARCH ALL.
- How to remove spaces from left, right and middle of string?
- Explain REDEFINES with COMP-3 example.
JCL Questions
- Difference between JOBLIB and STEPLIB.
- How to execute only selected steps in JCL?
- What is COND parameter?
- EVEN vs ONLY in COND parameter.
- How to restart a job from a specific step?
- How to check whether a file is empty in JCL?
- What is TYPRUN parameter?
- How to run job only on Monday?
- How to override PROC parameters?
- What happens if both JOBLIB and STEPLIB are coded?
- How to delete a dataset automatically in JCL?
- How to reference GDG versions across steps?
- How to restart a non-restartable step?
- Difference between cataloged and instream procedures.
GDG Questions
- What is GDG?
- Can we create GDG version with +2?
- What happens when GDG limit is reached?
- EMPTY vs SCRATCH in GDG.
- How to reference same GDG version in next step?
- If job abends, will GDG be cataloged?
- How to access oldest GDG version?
DB2 Questions
- What is a cursor?
- Cursor WITH HOLD vs WITHOUT HOLD.
- Difference between static and dynamic SQL.
- What is RUNSTATS?
- What is BIND and why it is required?
- Difference between PLAN and PACKAGE.
- Explain isolation levels.
- What is -805 error and how to resolve it?
- What is -811 error?
- What is -904 error?
- How to find 2nd or 3rd highest salary?
- How does DB2 restart logic work?
- What is deadlock?
- How to resolve deadlock in production?
- What is null indicator?
- What is phantom read?
VSAM Questions
- Difference between KSDS, ESDS, RRDS.
- What is Alternate Index?
- How to handle VSAM file status codes?
- Can VSAM file be used in batch and online?
- What happens if VSAM storage is full?
- How to copy VSAM file to sequential file?
- Can we delete record in ESDS?
CICS Questions
- Difference between batch and online programs.
- What is COMMAREA?
- How to pass control between CICS programs?
- What happens if cursor is not closed?
- How to set cursor position dynamically?
- What is PPT entry?
- How to kill a transaction in CICS?
Assembler Questions
- Explain SAVE AREA chain.
- Difference between LOAD and LINK.
- How to convert lowercase to uppercase?
- What are PSA, TCB, RB, SRB?
- How to obtain storage in CSA?
General / Scenario Based
- Production job abended – steps to resolve.
- How to do impact analysis?
- How to improve COBOL + DB2 performance?
- How to restart job after processing partial records?
- How to avoid deadlock?
- Difference between system and user abends.
- SOC1, SOC4, SOC7 – causes and fixes.
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