how to allot space on 6s

you don't. That's not a feature of iOS.

Stevein818 wrote:

how do you designate a specific amount of space on the 6s for certain uses? eg X gb for apps. X gb for audio etc?

you don't per se..... You want X amount for audio, then you only sync X amount for audi..

Check your storage on your iPhone, iPad, and iPod touch - Apple Support