parameter explanations

Hi all, where can I find more info about some Jena parameters like this ones?
Thanks for your help!

            DESCRIBE Query Strategy
            Indexes cleanup transaction size
            Jena TDB Block Read Cache Size
            Jena TDB Block Write Cache Size
            Jena TDB In memory query results
            Jena TDB Node Caches Size
            Jena index operation logging time threshold (in ms)
            Jena query operation logging time threshold (in ms)
            SPARQL Query abort timeout (in ms)

Joao