Hi Carol, It does not really matter where you are sailing, the principle is you need a warp at least three times the depth of water and if it is likely to be rough and windy you will need six times the depth. A chain length of 10m is more than enough but will help secure it well. Of course you also have to take into account the depth of the time. That should not be a problem in the med.
Lastly when anchoring in confined waters just thing about how much swinging room you have.