I ran the command vzctl set 101 --bindmount_add "/share:share" --setmode restart --save, but the "/share" folder from the host OS did not appear inside Container #101 after restarting.
The destination path in the bindmount_add option must be absolute, not relative.
The correct command to mount the "/share" folder from the host OS into Container #101 is as follows:
# vzctl set 101 --bindmount_add "/share:/share" --setmode restart --save
Be aware that '--setmode restart' will restart container after applying any parameters requiring that the Container be rebooted for them to take effect. Use '--setmode ignore' to restart container later manually.