Mainframe Developer Hiring Guide

Hiring Guide for Mainframe Engineers

Ask the right questions to secure the right mainframe talent, among an increasingly shrinking pool of talent.

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DASL (Datapoint's Advanced Systems Language)



DASL (Distributed Agent Simulation Language)


Cayenne (programming language)

Cecil (programming language)


CPL (programming language)

Cool (programming language)

Clarion (programming language)



Caché ObjectScript

Caml Light



Ada 2012Y2

Ada 2005X2

Ada 95X2

Alice ML

Ada 83X



Carnap (software)

Cardpeek Scripting Language for Lua.

Carbon Emacs Package for GNU Emacs on Mac OS X.

Car (programming language)

Capybara (web testing framework)

Cap'n Proto IDL

Candy (programming language)

Candl (programming language)

Campy (programming language)


Cameleon (programming language)

Calligra Stage Scripting

Cadence SKILL





C Shell

Concurrent Versions System



Bosque (programming language)







BCX Basic







GNU Guile

Erlang OTP

Erlang 23

Erlang 22

Erlang 21

Erlang 20

Erlang 19

Erlang 18

Erlang R17

Erlang R16B03

Erlang R16B03-1

Erlang R16B02






EusLisp Robot Programming Language

ECL (Enterprise Control Language)

EPL (Event Processing Language)








Bourne shell











Customize this hiring guideCustomize questions for your specific mainframe platform

First 20 minutes

General mainframe knowledge and experience

The first 20 minutes of the interview should seek to narrow-down the general background of the candidate, what environments they’re familiar with, and their approach to maintaining often aging and convoluted systems.

Can you describe your experience in mainframe development? What programming languages and tools have you used, and what types of applications have you worked on?

This question helps assess the candidate's level of expertise and their familiarity with mainframe development. It allows them to discuss their specific skills, technologies, and project experiences related to mainframe development.

Can you explain how you have ensured the performance and scalability of mainframe applications in your previous projects?

Mainframe applications often handle large volumes of data and require efficient performance. This question helps evaluate the candidate's understanding of optimizing mainframe applications for performance and scalability. Look for answers that include techniques such as code optimization, efficient database design, and performance monitoring tools.

How do you approach debugging and troubleshooting mainframe programs when issues arise?

Debugging and troubleshooting skills are crucial for mainframe developers. The candidate's response should demonstrate their familiarity with debugging tools, log analysis, and problem-solving techniques specific to mainframe environments.

How do you stay updated with the latest trends and advancements in mainframe development?

Mainframe technology continues to evolve, and it's important for a mainframe developer to stay current. The candidate's response should highlight their willingness to learn and adapt, such as attending conferences, participating in online communities, or engaging in professional development activities specific to mainframe development.

Have you worked on any modernization projects to migrate legacy mainframe applications to newer platforms? If so, can you describe your role and the challenges you faced?

Mainframe modernization is a common initiative in many organizations. This question helps gauge the candidate's exposure to modernization projects and their ability to adapt mainframe applications to newer platforms. Look for candidates who have experience with tools like COBOL-to-Java conversion or migration to cloud-based architectures.

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What you’re looking for early-on

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Next 20 minutes

Specific mainframe development languages

The next 20 minutes of the interview should attempt to focus more specifically on the development languages used, and the level of depth and skill the engineer possesses.

Mainframe environments often require efficient batch processing. Can you explain your experience with batch job scheduling and workload management tools, such as JCL (Job Control Language) and IBM z/OS Workload Manager?

Batch processing is a fundamental aspect of mainframe computing. This question evaluates the candidate's proficiency in batch job scheduling and workload management techniques. Look for candidates who can discuss their experience with JCL, job dependency management, workload balancing, and their ability to optimize batch processing performance.

In a highly regulated industry, how do you ensure mainframe systems comply with security and privacy standards? Can you elaborate on your experience with implementing security measures and managing access controls?

This question delves into the candidate's understanding of security and privacy considerations in mainframe environments. Look for candidates who can discuss their experience implementing security measures, managing access controls, securing data at rest and in transit, and their familiarity with compliance frameworks such as PCI-DSS or HIPAA.

Mainframe applications often have tight integration with external systems and applications. Can you discuss your experience with mainframe integration techniques and technologies, such as MQ (Message Queue) and Web Services?

This question aims to gauge the candidate's familiarity with mainframe integration approaches and technologies. Look for candidates who can discuss their experience with technologies like MQ or Web Services, as well as their ability to handle data exchange, real-time communication, and service orchestration between mainframe systems and external entities.

Mainframe systems often handle large volumes of data. Can you explain the techniques and considerations you use for efficient data storage and management on a mainframe platform?

Efficient data storage and management are critical in mainframe environments. This question evaluates the candidate's understanding of mainframe-specific data management techniques, such as VSAM (Virtual Storage Access Method), database partitioning, data clustering, and optimization techniques for data retrieval and manipulation.

Can you provide a detailed explanation of the different components and layers of a mainframe architecture? How do these components interact and contribute to the overall functioning of the system?

This question assesses the candidate's knowledge and understanding of the mainframe architecture in depth. Look for candidates who can articulate the various components such as Central Processing Units (CPUs), Input/Output Processors (IOPs), Channel Subsystems, and how these components work together to ensure efficient processing and data management.

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The ideal mainframe engineer

What you’re looking to see in the mainframe engineer at this point

By this time in the interview, the candidate should be really digging deeper in to their software development experience in COBOL, in a zOS platform. They should know syntax, approach, and possess a scientific approach to their work. “Winging it” or other cavalier / generalist responses should be seen as red flags.

Wrap-up questions

Final candidate for Mainframe Developer (COBOL) role questions

The final few questions of the interview are code questions, forcing a candidate to provide tangible, real-world answers to code related scenarios.

Can you describe your experience with mainframe system modernization or migration projects? How have you successfully integrated mainframe systems with newer technologies and platforms?

Mainframe modernization and integration with newer technologies are becoming increasingly important. This question helps assess the candidate's experience with modernization initiatives, their ability to integrate mainframe systems with modern technologies, and their understanding of best practices for bridging the gap between legacy and modern systems.

How do you approach mainframe security audits and compliance requirements? Can you discuss your experience with ensuring mainframe systems meet regulatory standards and industry best practices?

Mainframe systems often handle sensitive data and must comply with various security regulations. This question helps evaluate the candidate's familiarity with security audits, compliance requirements, and their ability to implement and maintain robust security measures on mainframe platforms.

Can you explain your experience with mainframe performance monitoring and capacity planning? How do you identify performance bottlenecks and proactively optimize mainframe applications?

Performance monitoring and capacity planning are crucial aspects of mainframe engineering. This question helps assess the candidate's understanding of performance monitoring tools, capacity planning techniques, and their ability to optimize mainframe applications proactively.

How do you ensure the reliability and availability of mainframe systems in a high-availability environment? Please describe your approach to disaster recovery planning and system backup strategies.

Mainframe systems often operate in high-availability environments where downtime can have significant consequences. This question helps evaluate the candidate's knowledge of disaster recovery planning, backup strategies, and their ability to ensure the reliability and availability of mainframe systems.

Can you discuss a complex mainframe project you have successfully led or contributed to? Please describe your role, the challenges you faced, and the outcomes achieved.

This question aims to assess the candidate's project management skills and their ability to handle complex mainframe projects. Look for candidates who can demonstrate effective leadership, problem-solving, and successful project outcomes.

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Mainframe Developer (COBOL) application related

Mainframe Developer (COBOL) modernization

Beyond hiring for your Mainframe Developer (COBOL) engineering team, you may be in the market for additional help. Product Perfect provides seadoned expertise in Mainframe Developer (COBOL) projects, and can engage in multiple capacities.

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