Docker container shared memory

Hi,
I understand that we can set the size of the shared memory on the container while spawning the docker images using the option shm-size as: docker run -it --shm-size=1g centos /bin/bash. But the question is

  • How much maximum memory can I set it to given that I am trying to spin up similar number of docker processes. Lets say 10 containers.
  • Does the size of the memory depend on the RAM of the host machine. And appx divided by the number of processes I intend to initiate?