– An asynchronous CF operation completes. GLYPH<SM590000> Dedicated ICFs GLYPH<SM590000> Shared ICFs GLYPH<SM590000> Dedicated CPs GLYPH<SM590000> Shared CPs The interrupt causes the receiving partition to be dispatched by an LPAR if it is not  dispatched. This process allows the request, signal, or request completion to be recognized  and processed in a more timely manner. After the image is dispatched, “poll for work”  logic in CFCC and z/OS can be used largely  as-is to locate and process the work. The new interrupt expedites the redispatching of the  partition. LPAR presents these Coupling Thin Interrupts to the guest partition, so CFCC and z/OS both  require interrupt handler support that can deal with them. CFCC also changes to relinquish  control of the processor when all available pending work is exhausted, or when the LPAR  undispatches it off the shared processor, whichever comes first. A CF image can have one of the following combinations that are defined in the image profile: Shared ICFs add flexibility. However, running only with shared coupling facility PUs (ICFs or  CPs) is not a preferable production configuration. It is preferable for a production CF to  operate by using dedicated ICFs. In Figure 3-13, the CPC on the left has two environments that are defined (production and  test), and each has one z/OS and one coupling facility image. The coupling facility images  share an ICF. The LPAR processing weights are used to define how much processor capacity each CF  image can include. The capped option can also be set for a test CF image to protect the  production environment. Figure 3-13 ICF options - shared ICFs Chapter 3. Central processor complex design  117 CF processor combinations