Coupling Facility Control Code is an IBM licensed Internal Code that always runs under an LPAR, regardless of whether the CF is in a standalone CPC or in a general purpose CPC (where CFCC LPs are together with z/OS LPs). A standalone CPC is a CPC only allowing LPs running CFCCs.
CFCC is a simple but efficient operating system where, for example, no virtual storage support is implemented. It has multiprocessing capabilities running multiple processors and when there is no work to do, it loops in the CF link waiting for work requests (the interrupt mechanism is not implemented).
CF – Coupling Facility
CPC – Central Processor Complex
ICF – Internal Coupling Facility
LIC – Licensed Internal Code
LP – Logical Partition
LPAR – Logical Partition