USDFLD with a cohesive element - ABAQUS

Hello,

I am intending to use the USDFLD subroutine to change the stiffness of the cohesive elements on the go (based on some solution parameters). So far, I had no luck in finding how to access the stiffness, modify and write it back. I am aware of the option of using a field variable to modify the stiffness, but in the present case, the stiffness may be a function of about three solution parameters.

So, any help would be appreciated.

Thank you.