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.
z/OS Communications Server: SNA Programming
Copyright IBM Corporation 1990, 2014