Complexity (SolverMaxMemory) defines the maximum available memory for the stiffness matrix.
It corresponds to the resolution of the model and thus determines the calculation time.
Increasing this values increases the resolution and thus calculation time!
It does not define the exact amount of memory the optimization uses, but the memory that is needed in the worst case if no material can be reduced due to the optimization setup.
You can either choose a percentage of your available RAM or an exact value.
Further information coming soon!