Standby Cache Reserve Bytes is the amount of physical memory, in bytes, that is assigned to the reserve standby cache page ...

Standby Cache Reserve Bytes is the amount of physical memory, in bytes, that is assigned to the reserve standby cache page lists. This memory contains cached data and code that is not actively in use by processes, the system and the system cache. It is immediately available for allocation to a process or for system use. If the system runs out of available free and zero memory, memory on lower priority standby cache page lists will be repurposed before memory on higher priority standby cache page lists.