content_image/989340.jpg
Note:  CFCC Change Shared-Engine CF Default to DYNDISP=THIN 

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 3-18. 

<img src='content_image/989340.jpg'>

For more information about CF configurations, see Coupling Facility Configuration Options , GF22-5042, and WP102400$^{16}$ Coupling Interrupt and Coupling Facility Performance. 

## 3.10 Virtual Flash Memory 

Flash Express is not supported on z15. This feature was replaced by IBM Z Virtual Flash Memory (VFM), from z14. The Virtual Flash Memory feature code is 0643 on z15. 

## 3.10.1 IBM Z Virtual Flash Memory overview 

Virtual Flash Memory (VFM) is an IBM solution to replace the external zFlash Express feature with support that is based on main memory. 

The “storage class memory” that is provided  by Flash Express adapters is replaced with memory allocated from main memory (VFM). 

