High Level Assembler: Interfaces.
This course covers the major OS/390 system services and their
application-programmer oriented interfaces.
The course is intended for:
- Experienced programmers - maybe new to assembler - needing to get
acquainted with available system services
- Assembler programmers needing to brush up on their skills
This overview comes in three parts, which are presented in sequence
below:
- Course Description
- Course Objectives
- Topical Outline
Recommended Duration: 3 Days
Benefits: Students who complete this course will be able to write or
maintain
Assembler programs that: process or create variable length records;
involve subroutine linkages; use dynamic serial linkages such as LINK,
LOAD, DELETE, XCTL; use other system service routines.
Students will also have a solid basis for debugging and dump reading
Assembler programs.
Audience: Experienced Assembler programmers needing to learn
additional support,
design, debugging, or maintenance skills.
Prerequisites: This course is intended as a follow-on to course
High Level Assembler: Classic.
Related IBM Materials.
This course is drawn from these IBM manuals; access to them in the
classroom is recommended but not required:
- GC28-1762 - Assembler Services Guide
- GC28-1910 - Assembler Services Reference
- SC26-4922 - Using Data Sets
- SC26-4913 - Macro Instructions for Data Sets
- SC26-4916 - Program Management
Major Topics Include:
- Program linkages and save areas
- Obtaining PARM data from the EXEC statement
- QSAM macros and processing
- SYNAD routines
- Subroutines and the Linkage Editor
- The Program Binder
- Debugging and dump reading
- Timing services
- The WTO, TIME, STCKCONV, CONVTOD macros
- The SNAP macro
- Managing print files
- Variable length records
- QSAM update in place (PUTX)
- Dynamic serial linkages: LINK, LOAD, DELETE, XCTL
- Virtual storage services: GETMAIN, FREEMAIN
Exercises: There are seven hands-on exercises
This course description Copyright © 2001 by Steven H. Comstock.
All rights reserved.
On successful completion of this course, the student, with the aid
of the
appropriate reference materials, should be able to:
- Follow standard OS/390 conventions regarding save area chaining
and the
passing and receiving of parameters
- Code or maintain Assembler programs that handle sequential files,
using
QSAM to read, write, and update records
- Write programs to handle variable length records using
QSAM
- Debug most program ABENDs, using OS/390 full dumps or symptom
dumps to
track down problems
- Write mainline programs and subroutines; use the Linkage Editor
to
combine mainline and subroutine programs
- Use the Linkage Editor or Program Binder to maintain load modules
by
replacing existing CSECTs with new versions of these CSECTs
- Use the WTO, SNAP, and TIME macros
- Use Dynamic Serial linkages (using LINK, LOAD, DELETE, XCTL) to
invoke
subroutines
- Use various other system services
(GETMAIN, FREEMAIN, STCKCONV, CONVTOD).
These course objectives Copyright © 2001 by Steven H. Comstock.
All rights reserved.
Day One
Program linkages
- Control Sections
- Save Areas
- Addressability
- Return Codes
- Typical Linkages
- SAVE and RETURN macros
- Getting the PARM value from EXEC statement
Working with files
- Data set organizations and access methods
- DCB Macros
- OPEN, GET, PUT, CLOSE
- Error handling: SYNAD routines
- ABEND macro
- Computer Exercise:
Basic Program Linkages and QSAM Files
Subroutines and the Linkage Editor
- CSECTs and the Linkage Editor
- Assemble, Link Edit, and Run Data Flow
- Anatomy of an Assembly Listing
- Assembler PARMs
- Subroutines: the CALL macro
- Object Modules and Load Modules
- Linkage Editor control statements and PARMs
- Managing Print Files
- Computer Exercise:
Subroutine Linkages
Day Two
Linkage Editor and Maintenance
- Impact of Changes to a Subroutine
- Additional Linkage Editor Control Statements
- Linkage Editor Processing
- Computer Exercise:
The Linkage Editor and Maintenance
Debugging and Dump Reading
- Computer Exercise:
ONION
- Guidelines for Debugging
- Program Termination
- IBM Publications
- BookManager
- READMVS
- Quick Reference
- File Related Messages
- Common System Completion Codes
- MVS, OS/390 Structure
- Essential Control Blocks
- Dump Reading
- Debugging: The Larger Context
Some System Services
- WTO - Write To Operator
- SNAP - Take a Snapshot Dump
- TIME - Get the Date and Time
- STCKCONV - Convert a STCK value to Date and Time Format
- CONVTOD - Convert a Date and Time value to TOD Format
Variable Length Records
- Defining
- Processing
- Computer Exercise:
Variable Length Records
Day Three
QSAM Locate Mode
- GET and PUT using locate mode
- Update-in-place: PUTX
- Extended Addressability Considerations
Dynamic Linkages
- Static Linkages
- Dynamic Linkages
- Module Attributes
- The Search for Modules
- LOAD
- DELETE
- LINK
- Reusable and Reenterable programs
- Computer Exercise:
Dynamic Serial Linkages
XCTL and Storage Management
- XCTL - an introduction
- GETMAIN / FREEMAIN
- Subpools
- XCTL Resumed
- Computer Exercise:
Using XCTL
Performance Improvements for Dynamic Linkages
- Use the DCB Parameter
- Build your own directory list (BLDL)
More Info
- Further Topics
- Further Sources of Information
This topical outline Copyright © 2001 by Steven H. Comstock.
All rights reserved.
Remarks? Questions? More information? Select the topic of your
choice or
e-mail us with your
questions.
To the Course Description
To the Course Objectives
To the Topical Outline
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