We address the anti-correlated vertical self-organization of stacked InAs nanowires grown on InP(001) using InAlAs as spacer layers. Using atomic force microscopy (AFM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy, we show that the lateral and vertical organization of the nanowires can be optimized by considering two main parameters: (i) the InAlAs spacer layer thickness (SLT) and (ii) the arsenic pressure during the InAs layer growth. With an optimal SLT/arsenic pressure combination, the nanowire size homogeneity can be improved, in ten-plane stacked structures with a SLT in the 10-15nm range, to achieve PL linewidths as low as 90meV at 8K, comparing to the 130meV linewidth obtained for single-plane structures.