In Immediacy, if you want to store global data you should be using the SiteOption feature from the Administrator. This is the place where all plug-in configurations are stored, as well as a bunch of other stuff.
If you’re writing your own custom C# plug-in and you need one of the SiteOptions, then you can use the Immediacy API to get the value for you. First, add a reference to Immediacy.Configuration, after that use the following code and enjoy!
ISiteOptions options = Immediacy.Configuration.SiteOptions.Instance;
SiteOptionGroup Option1 = options[“SiteOptionsName”];
(change “SiteOptionsName” to the value you want to get)