Connections between these z/OS and CF images can use internal coupling links to avoid the  use of real (external) coupling links, and get the best link bandwidth available. The  dynamic coupling facility dispatching  function has a dispatching algorithm that you can  use to define a backup CF in an LPAR on the system. When this LPAR is in backup mode, it  uses few processor resources. When the backup CF becomes active, only the resources that  are necessary to provide coupling are allocated. DYNDISP allows more environments with multiple CF images to coexist in a server, and to  share CF engines with reasonable performance. For more information, see 3.9.3, “Dynamic  CF dispatching” on page 149. CF work management and dispatcher changed to improve efficiency as processors are  added to scale up the capacity of a CF image. CF images support up to 16 processors. To obtain sufficient CF capacity, customers might be  forced to split the CF workload across more CF images. However, this change brings more  configuration complexity and granularity (more, smaller CF images, more coupling links, and  logical CHPIDs to define and manage for connectivity, and so on). To improve CF processor scaling for the customer’s CF images and to make effective use of  more processors as the sysplex workload increases, CF work management and dispatcher  provide the following improvements (z15): z15 supports 384 coupling CHPIDs per CPC (50% increase over z14). In addition, the CFCC  level 24 adds the following features: This feature is an enhancement to the internals of the Coupling Facility (CFCC) dispatcher  to provide CF work management efficiency and processor scalability improvements, and  improve the “fairness” of arbitration for internal CF resource latches across tasks. The tasks that are waiting for CF latches are not placed on the global suspend queue at  all; instead they are placed on latch-specific waiter queues for the exact instance of the  latch they are requesting, and in the exact order in which they requested the latch. As a  result, the global suspend queue is much less heavily used and thus is much less a source  of global contention or cache misses in the CF. Dynamic CF dispatching Coupling Facility Processor scalability GLYPH<SM590000> Non-prioritized (FIFO-based) work queues, which avoids overhead of maintaining ordered  queues in the CF. GLYPH<SM590000> Streamlined system-managed duplexing protocol, which avoids costly latching deadlocks  that can occur between primary and secondary structure. GLYPH<SM590000> “Functionally specialized” ICF processors that operate for CF images with dedicated  processors defined under certain conditions that realizes the following benefits: – One “functionally specialized” processor for inspecting suspended commands  – One “functionally specialized” proc essor for pulling in new commands  – The remaining processors are non-specialized for general CF request processing – Avoids many inter-processor contentions that were associated with CF dispatching GLYPH<SM590000> CFCC Fair Latch Manager2 Coupling Facility Enhancements with CFCC level 24 118  IBM z15 (8561) Technical Guide