The msgtql parameter specifies the maximum number of message headers system-wide, and thus the number of outstanding (unread) messages. One header is required for each outstanding message.
This parameter is specified in /var/sysgen/mtune/msg.
Value
Default: 40
Range: 10-1000
When to Change
Increase this parameter if you require more outstanding messages. Decrease the value to limit the number of outstanding messages.
Notes
If this parameter is too small, a msgsnd(2) system call attempting to send a message that would put msgtql over the limit waits until messages are received (read) from the queues.