COBOL Tutorials and Courses

Acronym for “Common Business Oriented Language.” COBOL is an imperative procedural & object-oriented language primarily used for business, administrative, and finance purposes. Applications such as large scale batch & transaction processing jobs that are deployed on mainframe computers, widely use COBOL. It cannot be used to work to write system software.

More than 70% of the business transactions that take place in the world today still rely on COBOL. The languages reside practically everywhere and interact with us nearly every day like stoplight and ATMs.

So here are some major reasons to learn COBOL:

• Easy to learn: The language employs verbs and sentences, thus making sense as the English language.
• Fast & Accurate: The language allows fast and straight-line data processing and provides rapid access to data. 
• Everlasting: The language integrates well with everything, so replacing it would be unnecessary as well as the world prove to be risky, expensive, and time-consuming.
• Easy to maintain: COBOL is easy to read & Maintain, thus allowing easier changes. It can be developed in an integrated development environment.
• Offers Opportunities: It offers great opportunities as it is associated with other programming languages and business components.

To begin learning a programming language, one must not necessarily begin with the computer background, but having it is always a plus. You can opt for various methods to learn COBOL. Some of them are:

• Online Tutorial: They are a number of tutorials online both paid & free for your self-learning.
• Books: Books are always a good option if you want to dig deep and learn descriptively.
• Instructor Training: This is helpful, especially for beginners, when you need someone to guide you along. 

The following books are recommended for learning COBOL:

• Beginning COBOL for Programmers 
• COBOL Software Modernization: From Principles to Implementation with the BLU AGE Method 
• DB2 for the COBOL Programmer
• Murach's OS/390 and z/OS JCL
• Murach's Mainframe COBOL
• Murach's CICS for the COBOL Programmer

The program is compiled, and a load module is created with all the sub-programs for the execution of the COBOL program in batch mode using JCL (Job Control Language). The JCL uses this load module at the time of execution and not the actual program. The concatenated load libraries are given to the JCL at the time of execution using JCLLIB or STEPLIB. The load module of the program is produced as output by JCL, which is used as the input to the execution JCL.

Static Call:

• In case of a static call, if any changes are there to any of the programs, then all the programs should be recompiled as the called program is link-edited to the calling programs load module.
• The program will take less time to run as it will not search for load modules in the load library during the run time if the size of the called program is less or few programs are called. 

Dynamic Call:

• The called programs have separate load modules in the load library and are compiled separately. Rest all programs need not be compiled, and only the required changing program needs to be changed if there are any changes to any called or the calling program. 
• If the size of the called programs is more, then it's wise to use dynamic calls. Though it will take little more time to run than the static call, it will still be flexible in the long run.

COBOL is data-oriented and was designed for business purposes and not a general-purpose language designed for development in mind. In those days of costly computer power, processing millions of transactions within a short time was the norm. For that purpose, batch processing was used, and COBOL was suitable for that. Moreover, COBOL resembles English in every context and looks like the mother tongue. And the main reason for the popularity of COBOL was decimal arithmetic, which was precise and accurate. We had problems of having 2.0 as being taken as 1.99 in FORTRAN. This was overcome by decimal arithmetic and was used for commercial applications.