I’m assuming that there is a need to dynamically configure things like the port in the parent’s environment. However, for an assembly tool, it might make sense to simply have it hard coded and save the extra complexity. My launcher script suggestion is a possible solution to this, but I would just hard code the port and ship it without a launcher myself. The suckless projects make use of hard coded configurations in their C programs. The principle is the same.

speculation: Maybe it's simpler to just bake a string into the binary and hardcode the pointer to at every use than futz around with strings in asm?

But if you're already doing the rest of it in asm why would that scare you?

Something you already have if you're building an http server in asm...