Learn PLI with Real Code Examples

PLI was created to handle structured programming for commercial applications on IBM mainframes.

It combines features from FORTRAN and ALGOL, with strong support for structured control, record handling, and input/output.

It was widely used in banking, insurance, and enterprise resource planning systems due to its reliability and performance on mainframes.

Procedures and subroutines

Arrays, tables, and records

Structured loops and conditionals

Built-in file and print handling

Static typing with mainframe-optimized compilation

Variables, constants, and data types

Procedures and modular routines

Arrays, records, and tables

Structured control flow: IF, DO, LOOP

Input/output and batch processing

Source/ - PLI source files

Bin/ - compiled object code

Lib/ - mainframe runtime libraries

Docs/ - documentation and specifications

Jobs/ - JCL scripts for batch execution

Write PLI source files with .pli extension

Define and implement procedures

Compile using mainframe PLI compiler

Submit jobs for batch execution

Verify results and debug as needed

Beginner: small data processing scripts

Intermediate: multi-procedure business applications

Advanced: mainframe batch system programming

Expert: maintaining large-scale legacy enterprise applications

Enterprise: mission-critical banking or insurance systems

More structured than early COBOL

Optimized for mainframe batch processing

Less portable than modern languages

Similar purpose as PL/I but IBM-focused

Strong legacy presence in banking and enterprise

1964–1965 – IBM develops PL/I and variants for enterprise

1960s–1970s – PLI widely adopted for mainframe batch systems

1980s – Legacy banking and insurance systems solidified use

1990s–2000s – Integration with modern mainframe technologies

2025 – Maintained in legacy enterprise and educational environments

Record: structured data type with fields

Procedure: reusable subroutine

Array/Table: indexed collection of elements

Batch job: program executed in mainframe job queue

JCL: Job Control Language for compiling and running jobs