VAX-11 PL/I User's Guide

This "VAX-11 PL/I User's Guide," published in August 1980, serves as a comprehensive manual for programmers using the VAX-11 PL/I compiler on the VAX/VMS operating system. Its primary objective is to describe the compiler's operation and the extensions made to the standard PL/I language to support the execution of PL/I programs within the VAX/VMS environment.

Aimed at programmers with a working knowledge of PL/I and familiarity with VAX/VMS DCL (Digital Command Language), the guide is structured into several key parts:

1. The Command Language (Part I): This section introduces fundamental VAX/VMS commands essential for PL/I program development. It covers the process of creating, compiling (using the PLI command with its qualifiers, handling concatenated files, and diagnostic messages), linking (using the LINK command, object module libraries, and system libraries like VMSRTL.EXE and STARLET.OLB), and executing PL/I programs (using the RUN command). It also details file specifications, temporary defaults, logical names for file independence, and methods for passing data to programs.

2. The File System (Part II): This part provides specific information on the VAX-11 file system, RMS (Record Management Services), and their relationship with PL/I input/output statements. It extensively covers ENVIRONMENT options for defining file attributes (creation, processing, disposition, and optimization) and I/O statement options (e.g., FIXED_CONTROL_FROM, PROMPT). It delves into file and record concepts, explaining sequential, relative, and indexed sequential file organizations, various record formats, and carriage control. Examples demonstrate creating, populating, updating, and accessing these different file types, alongside the use of built-in file-handling subroutines like DISPLAY, EXTEND, and REWIND.

3. Procedure Calling and Condition Handling (Part III): This section outlines the VAX-11 Calling Standard, which enables PL/I procedures to invoke procedures written in other programming languages. It explains various argument passing mechanisms (by immediate value, reference, and descriptor) and methods for handling character strings and optional arguments. The guide also details the use of global symbols (GLOBALDEF, GLOBALREF, VALUE attributes) for shared variables and provides extensive information on error signaling and condition handling through PL/I ON-units and VAX/VMS-specific extensions (ANYCONDITION, VAXCONDITION), including how ON-units can handle, resignal, or terminate program execution.

4. Programming Considerations and Examples (Part IV): This final part covers additional programming topics, such as storage allocation and usage (including program sections and managing storage within an area). It provides detailed examples of calling VAX/VMS system services (e.g., translating logical names, creating and deleting mailboxes, setting timers, implementing CTRL/C routines, and obtaining system information). It also explains how to access files on a network (remote file access and task-to-task communication) and how to call VAX-11 SORT procedures from PL/I programs.

The document is further supported by appendices that provide valuable reference material, including compiler and run-time messages, the correspondence between PL/I ENVIRONMENT options and RMS fields, and the ASCII character set.