Mainframes Interview Questions and Answers

Mainframes Interview Questions and Answers from Codingcompiler – In this article we have prepared the most frequently asked Mainframes Interview Questions and Answers for beginners and experienced by covering all the core areas by professionals.

Mainframes Interview Questions

  1. What is a mainframe?
  2. What are the various data types in COBOL?
  3. Define how the LIKE table could be created?
  4. Define DRDA?
  5. What is 77 level?
  6. Define WHERE and its usage?
  7. What Is Use Of Linkage Section?
  8. How To Get The Last Record In Vsam File In Cluster? And How Can U Get The Ksds File Records Into Ur Cobol Program?
  9. Name the units in the COBOL project.
  10. What is Mainframe Testing?

Mainframes Interview Questions and Answers

Q1) What is a mainframe?

Answer:A mainframe is also known as “big iron”. It is a large and multi-user computer device that helps to perform TIPS per second. Traditionally, mainframes were related to instead of distributed computing, Distinction is blurring smaller between traditional centralized computing and distributed computing because small computers become additional powerful and mainframes become additional multi-purpose.

Q2) What are the various data types in COBOL?

Answer: Alpha-numeric (fx), alphabet (a) and number (9).

Q3) Define how the LIKE table could be created?

The usage of LIKE parameter could create the LIKE table by the CREATE statement. These tables are usually required during the testing of the production environment.

Q4) Define DRDA?

DRDA means Distributed Relational Database Architecture. It is a connection protocol that is used for local database processing. IBM and other vendor database use it. It contains a set of rules which is used for communication between an application and a DBMS distant relation.

Q5) What is 77 level?

Answer: Startup item. Do not have subdivisions of other objects (can not qualify), or they can not separate themselves.

Q6)  Define WHERE and its usage?

The clause “WHERE” isolates a row or an element during the usage of a related system.

Q7) What Is Use Of Linkage Section?

Answer :Linkage section is used to accept data from outside the program.either it’s parm part of Jcl or Call from any other programs,they pass data into called program thru linkage section only.

Q8) How To Get The Last Record In Vsam File In Cluster? And How Can U Get The Ksds File Records Into Ur Cobol Program?


Move high values to the key of the VSAM file and the issue Readnext record command. Then give Readprev command. This will read the last record. In VSAM, there is one command HURBA, Using that we can read the last record, If you want to know more about go to IBM RED BOOKS. You will get the solution. by using the HURBA we can get the max records by using the CKD count key data we will get the last record.

Q9) Name the units in the COBOL project.

Answer: Identification Division, Environmental Division, Data Division, Practical Division.

Q10) What is Mainframe Testing?


Mainframe Testing is the testing of computer code services and applications supported by Mainframe Systems. Mainframe testing plays an energetic role in application development, overall development price and quality. Mainframe checking may be a part of end-to-end test coverage spanning platforms.

  • Mainframe Testing is sometimes performed on the deployed code victimization varied information combos set into the input data.
  • Applications that run on the mainframe are accessed through terminal somebody. The somebody is that the sole computer code that has to be put in on the shopper machine.
  • While activity Mainframe testing, the tester solely has to realize the navigations of the CICS screens. they’re custom-designed for specific applications.

Frequently asked Mainframes Interview Questions And Answers 

Q11) How are HIDAM and HDAM databases different?

HIDAM has its separate index file based on the root segment. This file stores information about the pointer that denotes the position of data. Whereas, HDAM does not have a separate index file. The key field of each record is accessed through a randomizer that positions the record in the correct place in the database.

Q12) What is referential integrity?

Referential integrity rule states that consistency needs to be maintained between primary and foreign keys. In other words, each foreign key needs to have a primary key.

Q13) What is mainframe development?

Mainframe development is software development, on a unique operating system, using obsolete tools and languages. A mainframe developer must know more than a programming language, he must know mainframe tools listed below and be comfortable working in the mainframe culture.

Q14) What is mainframe CICS?

Customer Information Control System (CICS) is a family of mixed language application servers that provide online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE. CICS is middleware designed to support rapid, high-volume online transaction processing.

Q15) What is DRDA?

DRDA (Distributed Relational Database Architecture) is a set of protocols or rules that enables the user to access distributed data regardless of where it physically stored.

  • It is an architecture developed by IBM.
  • It enables relational data to distribute among multiple platforms.
  • In DRDA, both like and unlike platforms can communicate with one another. Example DB2 subsystem can communicate with DB2 as well as RDBMS.
  • It provides an open, robust heterogeneous and distributed database environment.
  • DRDA provides techniques of coordinating communication among distributed locations.

Q16) Describe the benefits of DRDA?

The key benefits of DRDA are as follows.

  • DRDA is the only protocol that supports distributed RDBMS.
  • One significant benefits provided by DRDA is its clearly stated set of rules for supporting distributed data access.
  • It is available today, and many vendors are stepping up on the DRDA.

Q17) What is IMS?

The term IMS stands for Information Management System. It’s a database and transaction management system for Mainframe. IBM introduced it in 1968. Since then, it has gone through several upgradations and adapt some new programming tools and environments. IMS is one of two key legacy databases and transaction management subsystems from IBM that run on mainframe operating systems, and other is CICS.

Q18) Is Control Interval Descriptor Field present for each Control Interval?

Ans: Yes, Control Interval Descriptor Field present for each Control Interval.

Q19) Which of the following are attributes of the index component of the VSAM Control area?


  1. Index set
  2. Sequence set
  3. Both a and b
  4. Control set

CORRECT ANSWER : Both 1 and 2

Q20) What do you understand by lock contention?

As the DBD allows access to only one object at a given time, the concept of lock contention is said to come into the picture when more than one object tries to get access for simultaneous execution.

Advanced Mainframes Interview Questions and Answers for Experienced

Q21) What is WHERE used for?

HWhen an element or row needs to be isolated especially if used in conjunction with a relational statement, that is when WHERE is used.

Q22) What is the code for a deadlock?

The code used for a deadlock is 911 and 913. These are the SQL code for a deadlock.

Q23) What is the full form of SPUFI?

The full form of SPUFI is SQL Processing Using  File Input. This is a tool used by developers to create objects in the existing database. This is a menu-oriented tool.

Q24) Which are all the file OPEN modes?

The file OPEN modes are as follows… INPUT, OUTPUT, I-O and EXTEND

Q25) What is COMP-1? COMP-2?

COMP-1 – Single precision floating point. Uses 4 bytes.

COMP-2 – Double precision floating point. Uses 8 bytes.

Q26) What does the INITIALIZE verb do?

A: Alphabetic, Alphanumeric fields & alphanumeric edited items are set to SPACES.

Numeric, Numeric edited items set to ZERO.

FILLER , OCCURS DEPENDING ON items left untouched.

Q27) What Is Basic Difference Between “directory” And “pds” In Ibm Mainframe?

A: A PDS or Partitioned Data Set is a dataset containing multiple members, each of which holds a separate sub-data set, similar to a directory in other types of file systems. This type of dataset is often used to hold executable programs (load modules), source program libraries (especially Assembler macro definitions). A PDS is most somewhat analogous to a Zip file on microcomputers, except the files stored in a PDS are not compressed.

The Partitioned Data Set can only allocate on a single volume with the maximum size of 65536 tracks. Besides members, a PDS consists also of their directory. Each member can be accessed directly using the directory structure. Once a member is located, the data stored in that member is handled in the same manner as a PS (sequential) data set.

Top Mainframes Interview Questions and Answers 

Q28) What is COBOL?

COBOL is common business oriented language. It was language used by usa military named CODALYS. The language is a business language and is still in existence because of its ease and power to process huge data.

Q29) File1 has 100 records and file2 has 200 records i want to copy 50 records which r in both file into file3?

First need to sort both files


Q30)What is the distinction amongst INCLUDE and COPY?

Answer:  A minimal distinction is there in the way they work. They both help to extend design in a program. The central contrast is INCLUDE gets extended at PRE-COMPILATION organize itself and is the motivation behind why all DCLGEN individuals are extended utilizing INCLUDE.

Q31) Define the necessity of run stats among the environment test?

Answer: It is used for the clearing of the different values of the catalog columns. Since this column is already equipped with default values, the result may not be as expected.

Q32) What Is Label Record Is Standard Or Omitted In File Description Of Data Division?

Answer: Label record is standard means it will use disk files. But tape files can have a standard label too. If the label record is omitted it should be a tape file without any begin and end blocks on the tape.

Q33) Name and explain the type of locks?

Answer:  There are three types of lock, namely:

Shared: This type of lock permits two or more programs to read from the locked space but does not allow them to change it.

Update: This lock is more lenient. It permits the program to read and change the locked space.

Exclusive: This lock restricts all users from accessing the locked space.

Q34) How are composite and multiple indexes different?

Answer:  Multiple indexes is two indexes, one each for a column of the same table. A composite index is only one index, which consists of combined values of 2 columns of a table.

Q35) What is SPUFI?

First of all, SPUFI stands for SQL Processore Using File Input. This is a type of database provision, developed by the well-known IBM for the system that they provide, known as DB2. With the help of this users get to put the SQL commands directly into the TSO environment. This way they do not have to embed the commands of SQL into the program.

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