public static class SharedStrings
{
    private static Dictionary<int, string> myStrings;

    static SharedStrings()
    {
        myStrings = new Dictionary<int, string>();
        myStrings.Add(42, "hello");
    }

    public static string GetStringFromIndex(int index)
    {
        lock (typeof(SharedStrings))
        {
            return myStrings[index];
        }
    }
}