So, I’m not an expert but I will try to answer. Of course, this can be wrong and I ask the expert in this forum to correct me. Each particle distribution function (iPop) is commonly a double type (8 bytes). If you are using, for instance, the descriptor D3Q19 you have 19 double numbers to allocate on each lattice node. So, in this example, you will have 100000000198 ~= 15GB.
You can reduce this number using single precision numbers (float) or using a different lattice descriptor. Using a big computer with a lot of RAM will also help.
You also can ask yourself if you really need such a huge dataset.