Abaqus rolling simulations

Hi all,

 

I am modelling cold rolling in ABAQUS explicit and Standard. I am using plane strain elements as I am assuming, as is always the case, that the sheet is sufficiently wide compared to its thickness and therefore plane strain conditions apply. I am wondering what is the exact meaning of this ``plane stress/strain thickness" option when defining the section?

I can't find an exact definition of this in the documentation. Is this value just the width of my sheet? What difference does it make if I change it from 1 to 100?

Abaqus