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Assembler Cross Memory Services


4 hours


The z/OS – Cross Memory Services course describes the components involved in cross memory communications that allow a service provider’s address space to connect with a user’s address space. You will also look at the linkage stack and service provider coding with an emphasis on Program Call (PC) routines and the cross memory user. Finally, you will see how data is traditionally copied in a cross memory environment, and also look at how this is performed using Data-in-virtual.


System or application programmers who code Assembler programs or maintain system related programs and user exits; this course reinforces good Assembler programming techniques and introduces more advanced techniques including cross memory services, access registers and data-in-virtual.


Completion of the Assembler Introduction, Assembler Instructions, Assembler Macros and Assembler Programming courses plus a sound knowledge of programming concepts, and experience with IBM z/OS architecture.


After completing this course, the student will be able to identify:

  • Cross memory instructions and linkage
  • Cross memory clients and services
  • Access registers and Data in Virtual

Course Content

Cross Memory Addressing

Address Space Areas
Service Providers
Standard Program Calls

Cross Memory Service Routines

Functional PC Routines
Writing a Service Provider
Cross Memory User

Access Registers and Data-In-Virtual

Access Registers
Copy Access Instruction
Data in Virtual
Identify Service

Assembler Cross Memory Services Mastery Test