I was wondering why in appearance editor is not possible to define a resolution (output size) for the body and head skin higher than 2048x2048px
I understand the importance of low resolution for real time but I'm most interested in creating characters for high resolution render and this is a big limitation...
is there some workaround or some extension available?

thanks a lot for the detailed reply but perhaps I didn't explained myself in the correct way.
I know i can use external high res textures in iclone, what I would like to do is not use an external texture but try to export in high resolution (higher than 2048x2048px) the texture created by character creator, which  (if I understood well) is a procedural one and can be highly personalized with freckels, tan, normal for age and wrinkles. It's really a powerful tool to create custom body and face textures but it seem to me that it has this resolution limit..

Actually you are right in everything you say, and I usually work with 2 versions of the same textures, one low res tex for animating in iclone and one very high (like the ones coming from daz products) for final render which i usually realize within other software like cinema4d.
I need high resolution just because sometimes I need to render also small details of the character and if a 2048x2048px tex sometimes is enough for face textures, it is not when It comes to details of the body. When you see pixels in a closeup it's not a good thing.. 
My pc has no problem in managing procedural high res textures, anyway when I create the texture the way I want, I'm used to bake it before going into animation.
Anyway I know iclone and iclone cc are not focused on high res textures because their main concern is real-time animation, I was just wondering if the 2048px limitation of procedural skin (that i showed in the picture) can be overcame buying an extension like Essential Complete Bundle for Character Creation or if it is something more structural..