When asked about the state of assembler-language coding, many z/OS developers (especially the younger ones) would say it’s a thing of the past. Nothing could be further from the truth. The fact is most independent software vendors (ISVs) do a significant amount of their coding in assembler.
Why? Writing in assembler language has been described as “the closest you can get to the ‘brain’ of the CPU.” Like any assembler, not just with z/OS, assemblers are one-to-one correspondence between the instructions you write and the instructions that are executed on the machine. Other reasons to use assembler include:
- Code in great detail
- Easily Access system functions
- Reduce overhead and maximize performance
- System programming as opposed to application programming
Like all other operating systems, z/OS executes instructions based on the underlying hardware. Modern tools and languages make it easy to design and create complex applications and systems, but they also add layers of abstraction between the program and the machine on which it’s executing.
It’s often assembler-language code that is called upon for the most critical low-level or sensitive system functions. Performance, reliability, and other considerations may dictate the use of assembler code, and both z/OS components and many ISV products make extensive use of assembler routines and macroinstructions.
An understanding of how assembler code works, its conventions, when it’s needed (often required to invoke system functions and for product exit routines), and how an assembler listing can be used is an important skill for z/OS application and system programmers alike.
In the June webinar, DTS CTO Steve Pryor examines what a typical assembler listing looks like, what its most important features are, and how to use it for insights into the debugging process.
Learn More in our Webinar Available On-Demand
Our June webinar is now available on-demand in the DTS webinar library. As with each of our webinars, “How to Read a z/OS Assembler Listing” is a 60-minute informative and educational look at an important topic in the mainframe space. It includes numerous examples, how-to guides, and references on where to find more information should you need it.
If you weren’t able to attend or would like to review the material presented, you can view it on-demand and download a copy of the slide deck by using this link. And be sure to join us each month for our complimentary webinar series.