Where is the documention of the `-sshs` pwsh (or Subsystem?) command line switch?

All over MS and internet there is numerous examples of using the **`-sshs`** command option in the `sshd_config` file, like this: 
```powershell
Subsystem	powershell	c:/progra~1/powershell/7/pwsh.exe -sshs -NoLogo
```

However, I cannot find anything at all about what this does (or supposed to do).
Can someone please document this somewhere and point me to it?