Central processor
A general purpose processor on the mainframe, the kind that runs z/OS work of any type.
Also written CP, general purpose processor, GCP, mainframe processor
A central processor, or CP, is a general purpose processor on IBM Z. It can run any work: z/OS, batch, CICS, DB2 and everything else. When people talk about how many processors a mainframe has for z/OS, they usually mean CPs.
The physical processors in a machine are the same hardware. What each one is used for is set by its configuration: as a CP, or as one of the specialty engines such as a zIIP or an IFL. The machine is bought with a certain number of each.
CPs can also run at less than full speed, to match a customer's needs and budget. A machine's capacity setting describes how many CPs it has and at what level, and determines its rated capacity, the number behind MIPS and MSU figures.
This matters because software on z/OS is usually priced on the capacity or usage of the CPs. Work that can move to specialty engines does not count in the same way. When someone says a site "needs another CP" or "is CP constrained", they mean the general purpose capacity is fully used.
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- Specialty engineA mainframe processor set aside for one kind of work, such as Linux or certain z/OS workloads, and usually priced lower than a general processor.
- MIPSMillions of instructions per second: the common, rough way of describing how much processing capacity a mainframe has.
- PR/SMProcessor Resource/Systems Manager: the mainframe firmware that creates LPARs and shares the processors between them.
- LPARA logical partition: one physical mainframe carved into several independent virtual machines, each running its own operating system.
- IBM ZIBM's current family of mainframe hardware, and the brand name you will see on most modern mainframe job adverts.
- WLMWorkload Manager: the part of z/OS that decides which work gets the processor, memory and disk access first, based on goals the site sets.