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With the introduction of the Coupling Thin Interrupt support, which is used only when the CF partition is using shared engines and the new DYNDISP=THININTERRUPT  parameter, the CFCC code is changed to handle these interrupts correctly. CFCC was also changed to relinquish voluntarily control of the processor whenever it runs out of work to do. It relies on Coupling Thin Interrupts to dispatch the image again in a timely fashion when new work (or new signals) arrives at the CF to be processed. 

This capability allows ICF engines to be shared by several CF images. In this environment, it provides faster and far more consistent CF service times. It can also provide performance that is reasonably close to dedicated-engine CF performance if the CF engines are not CF Control Code thin interrupts. 

The introduction of thin interrupts allows a CF to run by using a shared processor while maintaining good performance. The shared engine is allowed to be undispatched when there is no more work, as in the past. The new thin interrupt now gets the shared processor that is dispatched when a command or duplexing signal is presented to the shared engine. 

This function saves processor cycles and is an excellent option to be used by a production backup CF or a testing environment CF. This function is activated by using the CFCC command DYNDISP ON . 

The CPs can run z/OS operating system images and CF images. For software charging reasons, generally use only ICF processors to run CF images. 

Dynamic CF dispatching is shown in Figure 3-16. 

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For more information about CF configurations, see Coupling Facility Configuration Options , GF22-5042. 

