Mainframe Blog

Mainframe MLC, Jobs/STCs, and Neapolitan Ice Cream – Part 1: How to Choose?

Jeremy Hamilton
2 minute read
Jeremy Hamilton

This is a special 3-part blog series focused on helping you better understand the best practices for identifying key drivers of your mainframe costs, using the most efficient technology available today.


Choosing a single flavor of ice cream on a hot day can be a tough choice, especially since there are so many choices. Finding ways to save on mainframe Monthly License Charges (MLC) can be even harder given how IBM charges for sub-capacity licensed software products and the complex nature of workloads running on the mainframe. IBM calculates the “peak” Rolling Four Hour Average (R4HA) of MSU utilization for a LPAR or combination of LPARs as the major charge factor when billing for MLC. Identifying work that can be rescheduled to run out of that peak, thus lowering the MSU count, can be a chore. What if the answer was a simple as Neapolitan ice cream?

Neapolitan ice cream contains three flavors in a single box. Comparing this to MLC, the box is your R4HA, and the ice cream is all of the workloads, or groupings of Jobs/STCs, which contribute to the hourly MSU count. Jobs/STCs have a MSU volume that contributes to the hourly MSU count and once the peak R4HA is identified, a cost can be associated to each of them.  So the question really becomes are Jobs/STCs running in the peak R4HA worth what you are paying for them?

In my household, a box of Neapolitan ice cream would mysteriously be emptied by preference; chocolate first, followed by vanilla, and lastly strawberry.  In the world of Jobs/STCs, the importance levels defined in the WLM service classifications frequently have very little bearing on if they can be rescheduled or not, tending to be more of a factor of SLA’s and dependencies. Movability coupled with cost makes it much clearer which would be more appetizing than others to reschedule from a cost savings standpoint. If we equate the workloads (Jobs/STCs) into ice cream flavors we have:

  • Strawberry – least likely to be moved, very little value
  • Vanilla – possible but not the first choice to move, somewhat valuable
  • Chocolate – easiest to move, most valuable

Obviously the Chocolate Jobs/STC would be the first place to look, but don’t be surprised if additional cost savings are found in the other flavors. This type of classification requires understanding, at a detailed level, what specific jobs/STCs are running in the peak, their cost-savings potential, and feasibility of rescheduling. The technical and business teams should work together to identify the Jobs/STCs to target and take scoop out of the peak R4HA!

Read more in Part 2. What Drives Peak and Monthly Cost?

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These postings are my own and do not necessarily represent BMC's position, strategies, or opinion.

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About the author

Jeremy Hamilton

Jeremy Hamilton

Jeremy has over 12 years of mainframe technical experience, with 5 of those focusing specifically on Mainframe Cost Optimization. He has served as a technical resource, Product Manager, and now as a Product Account Executive at BMC Software. He regularly speaks on MLC topics for customers, at SHARE and in IBM Systems Magazine webinars.