z/OS System Anatomy Part 3 - Structure & Flow

This course goes through how z/OS works inside - from IPL to end of job. It describes how MVS is set up internally during the IPL phase and then goes on to explain how virtual Address Spaces are created both for the MVS system itself and the real workload. These Address Spaces become the vehicles for all processing inside the system. The multi-tasking concept and TCB structure of MVS is discussed as well as all the services that an address space would typically ask for during its entire life, such as Job Management, ENQ/DEQ, Allocation, Virtual Storage and I/O operations. Behind-the-scene functions in MVS such as the SVC mechanism, Subsystem Interface (SSI), Cross-Memory Services (XMS) and the Recovery Termination Manager (RTM) with its ABEND processing are also covered extensively.


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

  • identify problem areas during an IPL
  • trace the task management control blocks in a dump
  • install and enable SVCs
  • understand problem and exit areas in job management
  • understand the issues surrounding GRS
  • use the subsystem interface
  • understand the problems in scheduling SRBs
  • resolve problems associated with Cross Memory Services
  • analyse storage control blocks in a dump
  • isolate I/O problem areas
  • exploit the Recovery Termination Manager.

Who Should Attend

Experienced MVS Systems Programmers who require an in-depth knowledge of MVS.


An in-depth understanding of the externals of MVS is required.


5 days

Fee (per attendee)

£2550 (ex VAT)

Course Code



An overview of MVS functions

MVS IPL and initialisation

LOAD command; Parmlib concatination; NIP and RIMs; Creating the PLPA; CVT.

Address Space & Task Management

TCB & RB - the foundation of multitasking; System Tasks in all Address Spaces (RCT, DumpTask & STC); The Initiator task; Program tasks.

Supervisor Call (SVC)

The SVC interrupt and the SVC First Level Interrupt Handler (FLIH); preparing for the SVC; the SVC Table.

Job Management

The 'Job Schedule' - JCL into the SWA.

Resource Control

GSR and Enqueue/Dequeue; MVS System Locks.

Subsystem Interface

The Master Subsystem (MSTR); Setting up the SSI.

Inter Address Space Communication

The conventional SRB; Cross Memory Services.

Main Storage Management

Virtual Storage Management (VSM); Real Storage Management (RSM); Auxiliary Storage Management (ASM); Extended Addressability - Data Spaces, Hiperspaces, VLF, LLA, DLF, Hiperbatch and Subspace Group Facility.

Input Output Processing

Access Methods (QSAM, BPAM, VSAM); The EXCP process; Input Output Processor (IOS).

Recovery Termination Manager (RTM)

Normal termination with EXIT (SVC3); System Failures and Functional Recovery Routines (FRRs); ABEND (SVC13) Processing and catching them with ESTAEs.

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