Originally posted by: CBird

I wonder if the parameter IloCplex.Param.WorkMem applies for the object from where it is called or if it is a setting for the optimizer.

Although it is counter intuitive to me, I have reason to believe, that it is a setting for the optimizer: I was solving 2 MIP's concurrently and CPLEX started to create node files. When I solved them sequentially, it did not. And when I solved them concurrently and increased the WorkMem parameter CPLEX did not create node files too.

The WorkMem parameter is per IloCplex instance. If you solve two models simultaneously with two instances of IloCplex then these two solves are completely independent. There must be another reason why CPLEX started to write out node files. Are you sure you used the exact same parameter settings in sequential and parallel solves?