- An EPS Seminar -

Dates and Location:

None scheduled at this time. Available for in-house instruction.

Hardcopy of Abstract and Outline:

EPSSeminarRileyAssemblerLanguagePart2.pdf

Additional Information:

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Seminar abstract and Outline

Audience:

This four-and-a-half-day seminar is the second of two ESA/390 and z/Architecture Assembler language seminars offered. It is designed as a follow-up to the entry-level Assembler Language Part 1 and is intended for application programmers working with assembler programs, and for system programmers responsible for interfacing with the z/OS operating system via user exit routines.

Seminar Instructor:

Phil Riley

Seminar Abstract:

The seminar introduces the student to assembler programming considerations such as addressability, parameter passing, extended addressing, inter-module communication and Linkage Stack usage. 64-bit addressing considerations are discussed where relevant, and various system macros are covered.

Other advanced topics, specific to the z/OS operating system, include the use of dataspaces to extend program addressability, the coding of a recovery routine to protect a program*s resources, plus considerations for writing shared programs for multiple concurrent users.

An important aspect of assembler programming is the diagnosis of failing programs. Students will be given instruction on using abend dumps to follow module flow leading to the point of failure, and to use effective diagnostic techniques for these dump types.

Lecture material is reinforced throughout the week with the use of lab exercises. These labs include SYSUDUMP analysis.

Prerequisites:

Students attending this seminar should possess a working knowledge of the TSO/ISPF editor, Job Control Language and assembler language coding syntax plus basic assembler mnemonics.

Seminar Objectives:

In this seminar, students will learn how to:

• Write exit routines to interface with z/OS operating system logic
• Perform addressing mode switching as required by program logic
• Use locate-mode techniques to perform Queued I/O operations in a program
• Transfer control across external modules in a given load module
• Use the Linkage Stack instead of the traditional save area to preserve a program's status
• Acquire and release additional virtual storage by the use of various macros
• Code logic and data structures permitting multiple users to concurrently execute a single copy of a storage resident program
• Write a recovery routine for a given module enabling that module to remain active even when a failure occurs
• Create and use one or more dataspaces thereby allowing a program to extend its available virtual storage
• Use IBM's AMBLIST service aid utility program to map a load module
• Use diagnostic techniques to analyze a SYSUDUMP abend dump

Seminar Outline:

The following is a high level outline for this seminar:

• Program Addressability
  • Control sections and Base-Displacement review
  • USING and DROP directives
  • Dummy sections
  • z/OS control block mapping structures
  
  
• Data Management
  • Coding for fixed and variable length data records
  • GET and PUT macros for move-mode QSAM I/O
  • GET and PUT macros for locate-mode QSAM I/O
  • OPEN, CLOSE and DCB macros
  
  
• Inter-Module Communication
  • Module communication within a static load module
  • "A" and "V" type address constants
  • CALL macro
  • Parameter passing using IBM standard rules
  
  
• Extended Addressing
  • RMODE and AMODE options
  • Addressing mode manipulation - BASSM and BSM instructions
  • Programming techniques to change addressing mode
  
  
• Linkage Stacks
  • Save Area review
  • Linkage stack concept and structure
  • Coding requirements for saving program status on linkage stack
  • BAKR and PR instructions
  
  
• Virtual Storage Management
  • Virtual storage subpools
  • GETMAIN, FREEMAIN and STORAGE macros
  
  
• Debugging Concepts
  • Load module structure and mapping
  • External symbol dictionary and relocation dictionary
  • AMBLIST service aid utility
  • ABEND, Summary and Symptom dump contents
  • ABEND macro
  • SNAP macro "LIST" parameter
  • Save area traces
  • Save areas with linkage stack entries
  
  
• Program Sharing
  • Module reusability, reentrancy and refreshability attributes
  • Standard, List and Execute macro formats
  • Use of external work areas
  • ENQ and DEQ macros
  
  
• Recovery Processing
  • Recovery routine overview
  • ESTAE macro
  • System Diagnostic Work Area control block
  • SETRP macro and standard parameter settings
  
  
• Dataspaces
  • Extending a program's virtual storage
  • Access vs. General register usage
  • DSPSERV and ALESERV macros