Learn Mainframe COBOL - Beginner to Expert

Explore the COBOL language structure—divisions, sections, paragraphs, sentences, and statements—and learn about characters, digits, A–Z, spaces, and allowed symbols.

Explore COBOL's enduring role in mainframe business apps, from report and payroll processing in banking and insurance to batch and online systems like CICS for reservations.

Discover COBOL's structured programming and English-like syntax that make code easy to understand and maintain. See how it handles millions of instructions per second on IBM machines.

Trace the history and types of COBOL, from mainframe origins to modern variants, and its use in banking, insurance, airlines, and stock exchanges.

Explore the COBOL coding sheet and the 80-column structure, including automatic line numbers, continuation and comments in column seven, and writing divisions, sections, paragraphs, and statements from column eight.

Identify the COBOL identification division, including program id, after date written, and date compiled, and learn its column and paragraph structure for mainframe programs.

Explore the environment division in cobol, focusing on the configuration section with old and object computer paragraphs, and the input-output section with file control and i/o control paragraphs.

Master the COBOL data division by declaring data items for the procedure division, and understand file section, working storage, and linkage sections, plus temporary and permanent data lifespans.

Declare variables in the working story section of COBOL's data divisions. Follow naming rules: 1-30 alphanumeric characters, start with a letter, no spaces or reserved words or special characters.

Explore COBOL data types—numeric, alphabets, alphanumeric, and sign—and observe numeric values right justified and alphanumeric values left justified, with the picture clause used to declare data variables in working storage.

Explore level numbers and how they organize data in the working-storage section, covering declarations, picture class, data types, and the special levels 66, 77, and 88.

Explore cobol data types in practical practice, declare variables in the data division, and pass values from console or files, covering alphanumeric and signed numeric types.

Learn how to define groups and elementary data names in mainframe cobol, including group level numbers from zero to forty-nine and declaring dates and alphanumeric items in working storage.

Discover how the 77 level number functions as a special type for independent data in real time on the mainframe, used to store raw number sequences, counters, or column numbers.

Learn how to assign data to declared variables in Cobol, distinguishing static and dynamic values, and pass data via terminal input or files, with real-world examples.

Learn how to handle input and output in mainframe COBOL by using accept and display in the procedure division, declaring data in the data division, and organizing logic with paragraphs.

Explore the simple move in cobol to transfer data between variables, accept terminal input, and display results, including guidance on group versus elementary data.

Learn how to compile, link-edit, and run a COBOL program on an IBM mainframe, creating a load module and executing with terminal input.

Explain how a group move copies all data from a group of variables to a destination, using group followed by elementary variables, unlike moving individual variables.

Explore the corresponding move in Cobol reference modification, transferring matching data items between groups. See how only corresponding variables move together, with salary, tax, and bonus examples illustrating data alignment.

Master reference modification in COBOL by moving partial data between variables with substring, a starting position and length, and using concatenation or splitting of fields, including date components.

Explore the string statement in COBOL to concatenate first and last names into a single customer name, using delimiter by size and a pointer to start at the fifth position.

Explore unstring in cobol, using one sending field to produce multiple receiving fields, delimited by comma or pipe, and compare with string concatenation and the pointer option for field positions.

Learn how to declare and display COBOL data items by defining numeric, alphabetic, and alphanumeric fields with picture clauses like 9(5) and 9(2), and test compilation.

Explore COBOL arithmetic operations, including add, subtract, multiply, divide, and compute for values; declare variables, display results, show division remainder, and handle a no memory error.

Explore editing characters in COBOL to format data for reports, using numeric, numeric with decimal, alpha, and alphanumeric types, with zero suppression, dollar signs, commas, and partial digit visibility.

explores 66 level number restatement to recouple elementary data items in a record, using renames to combine basic salary components, allowances, and deductions, and demonstrates practical COBOL coding patterns.

Learn how simple if conditions control COBOL programs by selecting statements and executing them conditionally, covering sequential flow, pseudo conditions, selection, and nested ifs with a salary tax example.

Explore how and or logical operators work in COBOL, using or to cover salaries above 3000 or below 3200 and using and to refine ranges within if statements.

Explore how the next statement bypasses steps when a condition is false, how true conditions jump to the next actions, how end statements display results, and how continue parallels next.

Learn how to replace nested ifs with the COBOL evaluate construct to handle multiple conditions, map month numbers to names, and compute days in a month.

Learn debugging and proper use of the cobol evaluate statement by removing dots and correcting conditions, then display John and calculate the days in a month (February 28).

Learn about level number 88 in COBOL, a special low level number used with 0–49 or 77 values to simplify multiple condition checks via if and evaluate statements, improving readability.

Learn to reuse existing storage in cobol by using redefines to reuse variables, avoid unused allocations, and optimize storage through grouping and compression.

Learn how comp1 and comp2 numeric usage compresses storage space and speeds processing in Mainframe COBOL, by optimizing memory for display, decimal, binary, and hexadecimal data.

Explore mainframe cobol comp-3 numeric storage and packed decimal handling. Understand how s9 packed decimal occupies half-byte storage and when numeric data differs from alphanumeric data.

Learn to use the COBOL procedure division's reusable paragraphs and perform statements to control program flow, including outline perform, in line perform, perform times, and perform until.

Explore inline perform in COBOL with simple perform, perform until, and inline variants, showing how statements execute in line, outputting values and looping with incremental logic.

Examine the various outline forms of perform in COBOL, including simple perform, perform times, and perform with through and until, calling paragraphs and using exit and stop run.

Compare inline perform and outline perform in COBOL, noting scope termination and placement. Use inline for lower volumes and outline for large volumes, with attention to exit statements.

Learn how occurs creates a one-dimensional array of similar data items in COBOL, with a subscript to access months or hourly values and a rule about 01 or 77 numbers.

Learn to work with COBOL arrays from one to three dimensions by declaring occurs, using subscripts, and storing month, week, and day data with practical bank and timing examples.

Learn how to perform a linear search in a mainframe cobol table, scanning customer records by name or account number, and display matches or no records found.

Explore binary search in COBOL using a one-dimensional array sorted in ascending or descending order to locate a target with the equal to relation operator, contrasting it with sequential search.

Compare subscript and index in COBOL arrays, and learn how search and search all affect data retrieval from a table, including declaration, displacement position, and access speed.

Explore the Cobol file concept, storing data permanently with files, records, and fields, and learn the file lifecycle from declaration to processing in mainframe programs.

Master the filler concept, learning how to reserve blank space within a data record to accommodate future layout changes and evolving fields.

Read employee records from a 36-byte flat, sequential file using COBOL, opening, reading, and closing the file while tracking file status for end-of-file and successful reads.

Open the output file in write mode, accept employee records (id, name, location, salary), and write them to the file, verifying that records are stored.

The lecture shows updating an employee salary in a COBOL file: open for input, locate by id, add ten thousand, and rewrite the record.

Discover how copy books define reusable file records as replaceable members, enabling shared input and output structures to reduce code duplication and improve COBOL program productivity.

Demonstrate calling a subprogram from a main COBOL program, passing actual and formal parameters by reference or by value, and illustrate how the linking section connects them.

Explore the difference between copy and call in mainframe cobol: copy embeds predefined code in any division, while call invokes a subprogram from the procedure division, parameter handling and linking.

Explore internal and external sorting in COBOL, detailing ascending and descending keys, input and output files, work areas, and the merge of two inputs into a sorted output.

Debug and run Cobol sort and merge programs by fixing input-output mismatches, declaring correct record sizes, compiling, and validating that data records are sorted into output files.

Explore the inspect function to scan strings, count occurrences and leading or trailing characters, identify holes, replace characters, and apply string operations in a mainframe cobol program.

Explore mainframe COBOL ESDS file read and write, demonstrating reading from an input file, copying records to an output file, and handling fixed 48-byte records, record structures, and file status.

Fix the ESDS file read/write COBOL program by correcting the final attribute mismatch and applying the proper file naming format, then recompile and run to process four records.

Explore ksds read and write operations by examining a cobol-style program that opens input and output files, defines keyed student records, and performs read and write cycles with status checks.

Compile and execute a KSDS read/write COBOL program, reading 48-byte records with 4-byte keys and writing to an output file. Debug end-of-file logic to ensure all records copy.

Fix and verify KSDS read and write logic in a mainframe Cobol program, ensuring the last-record write executes correctly and all records display as complete.

Explore ESDS COBOL programming and ESD file transfer, compare random access data with sequential record keeping, and apply the related logic as practiced in this session.