Installed MIPS growth has averaged 10 to 20 percent per year, Linux on z –appx. 20% of net new MIPS being shipped.
Gartner 2010:

Though we firmly believe that z/OS will remain the mainstay of Enterprise Class systems on IBM mainframes for very many years to come, anyone not already exploiting Linux for System z on these Enterprise Servers is not making the most of the asset they have already invested in.

You’ve spent a lot of your IT budget on the System z environment, to not extract every last ounce of compute power from this environment and put it at the disposal of your business applications is to throw money away for no benefit.  Your CIO needs to understand how Linux on System z can reduce your overall IT infrastructure spending, freeing up resources for more interesting and pressing business priorities and projects.

Our consultants at LongDivision are specialists in helping you identify, qualify, quantify and prepare the business case for implementation of workload on your System z.  We can help you demonstrate to your executive the potential savings of taking the path of mainframe systems consolidation.  Then we can help speed and smooth the migration of software and processing from alternative Unix and Linux based environments to your System z.