available Elements in a DMA FIFO

Hi, 

I had a problem with reading from a DMA FIFO on the host. My main question is if the available elements not he buffer depend on the resources that are used on the FPGA target. 

As I can see, the number of elements that I can request to read in a DMA FIFO read method is limited. But I wonder if it depends on the other resources that I use on my target code, (not just the other DMA FIFOs that I use, but the other FIFOs and memory blocks, ...). 

If it is the case, are there ways to see how? I can stop using the other resources (FIFOs, ...) when I want to use the DMA FIFO, but is there a way to idle or mute them? 

I am using a NI USB-RIO 7856 anf LabVIEW (FPGA) 2018.