msg_set_queue() allows you to change the values of the msg_perm.uid, msg_perm.gid, msg_perm.mode and msg_qbytes fields of the underlying message queue data structure. You specify the values you require by setting the value of the keys that you require in the data array.
Changing the data structure will require that PHP be running as the same user that created the queue, owns the queue (as determined by the existing msg_perm.xxx fields), or be running with root privileges. root privileges are required to raise the msg_qbytes values above the system defined limit.
See also msg_remove_queue(), msg_receive(), msg_stat_queue() and msg_set_queue().