[This is preliminary documentation and is subject to change.]
Assembly: cai-nmgen (in cai-nmgen.dll) Version: 0.4.0.0 (0.4.0.0)
Prevents the formation of meshes that are too small to be of use.
If you really don't want or expect any island regions, then set this parameter to a high value. Otherwise the value will depend entirely on your needs.
In the example below, the value has been set too low, allowing the formation of small meshes on the top of obstructions.