Ushnish Basu
Ansys Employee

The pressure cutoff value comes from the material, e.g. MAT_NULL has a PC parameter which is passed on to the EOS

You can see it's use in the standard umat44v (note the common block where it is stored)

If you want to use a user material with a built-in EOS, you can combine them in the PART card

Make sure to set the NHV for the material to be 4 larger than what you actually need, and start your material history variables (in hsv or hsvs) only from the 5th position. The first 4 positions are reserved for EOS variables such as internal energy, bulk viscosity and current volume. 

The EOS calculations are done after the user material routine is called, so there's not direct way to get the pressures calculated in that step. However, you can get the pressure for the previous step from the stress tensor at the beginning of the step.