It was in Milli-Com that the Rogue Trooper and his comrades Gunnar, Helm and Bagman first saw the light of what passes for day in its artificially-lit chambers and corridors. Its scientists were so desperate to win the war that they not only created a whole new type of human being — possibly a new species, Homo caeruleus — but also found a way to preserve someone's personality and memories on a silicon chip in their brain that would then 'live' if removed post-mortem and placed in a piece of military equipment. In peace time this would definitely have gained them at least one Nobel prize, but as they were at war the new humans created on Milli-Com were used as cannon fodder (the men) or sex toys (the women, such as Venus Bluegenes and Azure).
Still, life isn't all strictly utilitarian on Milli-Com. It is licensed as a wedding venue, there is a bar serving strange cocktails called 'green genes', and according to Helm there is a disco on deck 54.
Any resemblance to the Death Star is entirely coincidental.