z/OS Diagnostics & Debugging

This course provides attendees with an effective and systematic approach to z/OS problem diagnosis. In the course the z/OS software environment is examined by looking at the Recovery Termination Manager (RTM) - the 'cleaning-up' function of MVS - and its ABEND-concept. All the different reports that come out of a z/OS system, in conjunction with failures (messages, dumps, traces, etc.) are also discussed. System ABENDs, and how you can analyze the information coming out of the system when they occur, is also covered.
Attendees will learn how to identify system problems promptly, in order to provide greater system availability. The course focuses on a debugging methodology using IPCS. Practical workshops provide an opportunity to learn to debug system problems in realistic situations.

This course is also available 'on demand' (minimum 2 students) for public presentations or for one-company, on-site presentations.

What you will learn

On successful completion of this course you will be able to:

  • report problems and communicate with applications personnel and systems programmers
  • understand what the Recovery Termination Manager (RTM) does when programs fail
  • understand the concept of an ABEND
  • analyze ABEND-situations
  • use the appropriate diagnostic procedure for each type of dump
  • identify the failing operating system component in standalone and SVC dumps
  • use various operating system data-gathering facilities such as system traces, LOGREC, and SLIP
  • locate information in various manuals that is critical to problem resolution
  • use the tools available in order to resolve common system abends without Dumps.

Who Should Attend

This course is suitable for all Systems Programmers working in the zSeries Server environment.


To benefit from this course, participants need the ability to read Assembler code and familiarity with z/OS internal operations and data areas, including the concept of control block chaining. These prerequisites can be met by completing the courses Using z/OS Assembler, z/OS System Anatomy Part 1 - zArchitecture and z/OS System Anatomy Part 2 - z/OS Infrastructure & Services.


5 days

Fee (per attendee)

£2250 (ex VAT)

Course Code



z/OS Software Environment

The z/OS environment - a lot of programs; three software categories; the mission of an Operating System; workload in z/OS; asking for z/OS services; asynchronous z/OS activities; asynchronous "unwelcome" z/OS activities; summary; review questions.

Recovery Termination Manager (RTM) Overview

Normal Program Termination; EXIT (SVC 3); abnormal program termination; Program Checks; system forced ABEND; program ABEND; why abnormal termination?; logical application error; program incomplete; application detected software error; system detected software error; hardware detected software error; PC FLIH and ABENDs; hardware detected software error example; Program Checks in the Supervisor; hardware problems; RTM actions; recovery; Functional Recovery Routines (FRRs); Extended Specify Task Abnormal Exit (ESTAE); system breakdown; software problem types; review questions.

z/OS Error Reporting & Dumps

System error reporting; MVS dumps; Stand-Alone Dump (SADUMP); SVC dumps; user ABEND dumps; SYSUDUMP; SYSABEND; SYSMDUMP; CEEDUMP; generating a user ABEND dump; system generated ABEND dump; snap dumps; symptom dumps; review questions.

System ABEND Analysis

What is ABEND?; how RTM is invoked; program checks; how to trigger an ABEND; the symptom dump; ABEND dumps; explanations of ABEND and reason codes; analysis approach; system messages; system message prefix; message level; standard message types; common system ABEND codes; analysing individual abend codes.

IPCS for SVC Dumps and Stand Alone Dumps

Control block/data area; Information sources; Control block header; Control block data area map; Cross reference table; Fields and subfields; Field redefinitions; Control block chaining; Finding control blocks; The Prefix Area (PSA); The new Prefix Area (PSA); Dump types; IPCS introduction: what is IPCS?, What makes up IPCS?; Getting started with IPCS - Primary Option Menu; Default values selection; Primary Option Menu; Data entry panel; Pointer stack panel; Getting around in IPCS browse; IPCS subcommand entry panel; IPCS command output display; IPCS LIST command; Indirect addressing; Displaying Control Blocks; Creating SYMBOLS: Dump Directory; Additional Useful Commands; Dump analysis panel; Component Data Analysis Panel; STATUS; Analysis commands; Dump Management panel.

RTM and Software Logrec

MVS's recovery management; RMS; What does RTM do?; Interrupt types; Anatomy of an Interrupt; RTM - The Big Picture; How is RTM invoked?; Normal termination; Abnormal termination - problem types; Program check; Software 'Abend'; Abnormal termination - recovery; Recovery routines; RTM status information; ESPIE environment; ESPIE processing; ESTAE recovery routines; ESTAE environment; STAE Control Blocks (SCB); ESTAE processing; Percolation; Functional Recovery Routines; FRR environment; FRR stacks; RTM2WA; SDWA; Variable Recording Area; Interpreting the SDWA; Interpreting the Variable Recording Area; Logrec detail reports.

Request Block (RB) Analysis

Address space structures; RB loss of control; Linkage stacks; RB analysis procedure; Linkage Stack analysis; General analysis; RB analysis.

System Trace

Starting the System Trace; Formatting the Trace; Sequence of events; Interpreting the Trace; System Trace tips.

SVC Dump Approach

Generating SVC dumps; Dump Analysis and Elimination; Types of SVC Dump; Problem resolution overview; Dump TITLE; SDWA; History; RTM2WA; Other dumps.

MP Environments

Tightly coupled processing; Prefixing; Processor coexistence; Processor STATUS; Work In Progress; Interrupt information.


The problem; An example of what can go wrong; Serialization via LOCKS; Lock varieties; Locking Hierarchy; Locking Mechanics (SPIN); Spin Loop Identification; Spin Lock Holder; Local/CML Locks; Locking Mechanics; Global Suspend Locks ANALYZE; Locks Held; Locking Mechanics (CPU LOCK); SPIN lock summary; SUSPEND lock summary.


What does it mean to be dispatched?; Where does the dispatcher run?; Dispatchable units of work; Who calls the Dispatcher?; Special exits; Service Request Block routines; Service Request Block (SRB); SRB example - IOS post; Service Request Block (SRB); Suspended Service Request Block (SSRB); SRB priorities; SRB scheduling with IEAMSCHD; SRB enclaves; Dispatcher queues; Scheduling service requests; Address spaces; ASCB/ASXB contents; Finding work within an address space - tasks; TCB contents; TCB chaining; Address space task structure; Serialization with Intersect; Dispatcher indicators; Global problem determination; Global indicators - SRB queues.

Consoles and Master Trace

Message generation; Console structure; Messages; Message Queue problems before SADump; Message queue problems after SADump; Action Messages; Master Trace; Interpreting the Master Trace; Console Component Analysis.

Input/Output Supervisor

IOS drivers; Performing I/O; I/O flow; IOS analysis - high level; Active I/O analysis; IOS failure analysis.

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