Abstract for SNA Programming
Purpose of this information
This manual describes programming concepts and VTAM® macroinstructions. Use it as a guide when designing and coding application programs. This publication covers all macroinstructions except APPCCMD (see the z/OS Communications Server: SNA Programmer's LU 6.2 Reference) and macroinstructions related to the installation of VTAM (see the z/OS Communications Server: SNA Resource Definition Reference).
This document supports z/OS®.e.
Who should read this information
This document is designed to help programmers (such as application or system programmers) write application programs that use VTAM macroinstructions.
How this information is organized
This document
contains the following chapters:
- VTAM application program concepts provides an overview of a VTAM application program.
- VTAM language contains the following:
- Characteristics of the VTAM language
- A summary of the VTAM application program macroinstructions
- Relationships among the VTAM control blocks as well as their relationship to the macroinstructions
- A description of a normal operating system environment for a VTAM application program
- Organizing an application program discusses the following:
- General coding guidelines to consider when writing an application program
- Coding guidelines to facilitate migration of application programs
- Whether the application program should be single-thread or multithread
- Whether the application program operation should be synchronous or asynchronous and what posting mechanism should be used
- VTAM and user control block decisions to be made that affect application program organization
- Opening and closing an application program describes aspects of the OPEN, CLOSE, and ACB macroinstructions that apply to all application programs.
- Establishing and terminating sessions with logical units describes how VTAM establishes and terminates a session between LUs.
- Communicating with logical units provides a general description of communication facilities.
- Using exit routines discusses how exit routines work, presents some of their advantages and disadvantages, and describes procedures to follow in using them.
- Setting and testing control blocks and macro global variables discusses the ways in which the VTAM application program sets and tests control block values.
- Handling errors and special conditions discusses how to analyze information for errors and special conditions and what to do, in general, when the error or special condition is identified.
- Operating system facilities describes a number of operating-system-dependent facilities to use when writing a VTAM application program.
- Programming for the IBM 3270 Information Display System describes VTAM application programming for sessions that use LU type 0 protocols.
- Coding for the communication network management interface describes the coding required for an application program to function on the communication network management (CNM) interface.
- Conventions and descriptions of VTAM macroinstructions describes the format of the macroinstructions and then presents each macroinstruction in alphabetical order.
- Logic of a simple application program shows the logic of a VTAM application program that receives a request for a session with a logical unit (LU), establishes the session, reads input from any session, processes the input, prepares a reply for output, and writes the output on the session.
- Sample code of a simple application program contains the assembler language instructions for a VTAM application program, SAMP1.
- Logic of a more complicated application program contains a more typical example of a VTAM application program than SAMP1.
- Sample code using authorized path contains sample program, SAMP3, which shows an application program using the authorized path facility under the control of both a task control block (TCB) and a service request block (SRB).
- Summary of control block field usage serves as a reference for the experienced VTAM application programmer by showing the information for each executable macroinstruction discussed in this document.
- Return codes and sense fields for RPL-based macroinstructions provides information about return code posting and explains what the different return code and feedback field values mean. It also provides information about SNA sense fields.
- Summary of control requests and indicators contains tables that summarize the SNA control requests and indicators sent and received by VTAM application programs.
- Request and response exchanges for typical communication operations contains diagrams that show the sequences in which requests and responses are exchanged to perform typical data communication operations using VTAM.
- Control block formats and DSECTs contains file description control block formats and DSECTs.
- Specifying a session parameter describes the format of the session parameter as seen by a VTAM application program.
- RPL fields associated with VTAM macroinstructions shows fields modified by the SEND and SESSIONC macroinstructions.
- Summary of register usage shows what VTAM does with the general-purpose registers before it returns control to the application program at the next sequential instruction.
- Return codes for manipulative macroinstructions explains return codes for manipulative macroinstructions.
- Summary of operand specifications indicates which manipulative macroinstructions apply for each operand and the types of values that can be coded with each operand.
- Forms of the manipulative macroinstruction summarizes the actions of various forms of manipulative macroinstructions.
- Program operator coding requirements describes how to write the program operator portion of a VTAM application program using the SENDCMD and RCVCMD macroinstructions.
- List of macroinstructions contains macroinstructions provided as programming interfaces by VTAM. Do not use as programming interfaces any VTAM macroinstructions other than those identified in this appendix.
- Application program migration describes factors to consider in various migration environments.
- "Architectural specifications" lists documents that provide architectural specifications for the SNA protocol.
- "Accessibility" describes accessibility features to help users with physical disabilities.
- "Notices" contains notices and trademarks used in this document.
- "Bibliography" contains descriptions of the documents in the z/OS Communications Server library.