Windows 10 users should be on the lookout for a new automatic update that Microsoft is pushing out to the OS. This update is specifically for the servicing stack, but details about what it contains have not been revealed.

Microsoft's support page says:

This update makes stability improvements for Windows 10 Version 1511 servicing stack. If you are installing a servicing stack update package for the first time, the package for the x86 version is 5 MB and the package for the x64 version is 11 MB.

This is not a culmuatve update for Windows 10, so there's no new version number once the servicing stack update is installed. It also doesn't require rebooting your PC.