Windows Kernel-Mode Executive Support Library
The Windows operating system uses the term executive layer to refer to kernel-mode components that provide a variety of services to device drivers, including:
Process and thread management
Each of the above managers provides direct interfaces to their individual technologies, as do several libraries. However, routines that are grouped together as a generic interface to the Executive Library are usually prefixed with "Ex", for example, ExGetCurrentResourceThread. For a list of executive library routines, see Executive Library Support Routines.
Note that the executive layer components are part of Ntoskrnl.exe, but that drivers and the HAL are not part of the executive layer.