Technical screening questions
Ask for one example per question and listen for specifics.
- How do you debug a batch abend? A good answer: Reads the abend code, the dump and the job log, then isolates the step.
- How do you tune a DB2 query? A good answer: Explain output, indexes and access paths.
- What is the difference between a batch and an online (CICS) program? A good answer: Scheduled processing versus interactive transactions.
- How do you work with VSAM files? A good answer: KSDS and ESDS types and access methods.
- What modernization work have you done? A good answer: Interfaces, rewrites or migrations with specifics.
Quick screening questions
Use these when you have only a few minutes.
- Years on COBOL and which industry?
- Batch or online (CICS)?
- Any modernization or migration experience?
What separates the levels
Match the level to the requirement before you submit.
- Junior: fixes defects in existing programs.
- Mid: develops and tunes batch and online code.
- Senior: leads migrations and design.
Red flags
Any of these is a reason to probe further.
- Cannot read a JCL step.
- Training exposure only.
- No production support experience.
Tools you should hear mentioned
A Mainframe developer with real experience usually names several of these without prompting.
- COBOL
- JCL
- DB2
- CICS
- VSAM
- z/OS tools (ISPF, File-AID)
Run the call well
Ask for the last project first, then dig into the second or third question. Take notes on versions, team size and outcomes, and record them with the submission so the vendor’s later technical interview does not surprise you.
Frequently asked questions
How long should a Mainframe developer screening call take?
Fifteen to twenty minutes is enough to cover the project, three technical questions and availability, rate and work authorization.
Do recruiters need to know the technology?
Working vocabulary is enough. Use the sourcing guide for the role and listen for specifics instead of judging technical depth yourself.