nclist(5) File Formats Manual nclist(5)
NAME
nclist - number of cblocks for pty and tty data transfers
VALUES
Default
Allowed Values
Minimum Maximum limited by available memory.
DESCRIPTION
specifies how many are allocated in the system. Data traffic is stored in as it passes through tty and pty devices.
The default value for is based on a formula of 100 for system use in handling traffic to the console, etc., plus an average of 16 per user
session, assuming 512 user sessions. are also used for serial connections other than login sessions, such as as SLIP connections, UUCP
transfers, terminal emulators, and such. If your system is using these other kinds of connections, should be increased accordingly.
If the pool is exhausted, data being passed through a tty or pty device might be lost because a was not available when it was needed. If
this occurs, the warning message "cblock exhaustion has occurred n times (see termio(7)) is placed in the system message buffer.
Who Is Expected to Change This Tunable?
Users with the privilege. See privileges(5) for more information about privileged access on systems that support fine-grained privileges.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
The tunable value can be increased in the following instances:
o When the kernel sends the error message the system is running out of This indicates that needs to be increased.
o The system may run slow for terminal I/O resulting in some data loss, without displaying a warning message. Increasing the value
may solve this problem.
The minimum value for is There is no maximum, but each consumes 32 bytes of resident (non-swappable) machine memory, so the value should be
selected with this in mind.
What Are the Side Effects of Raising the Value of This Tunable?
More resident (non-swappable) machine memory is used.
When Should the Value of This Tunable Be Lowered?
This value should be lowered when a minimal system is being created.
What Are the Side Effects of Lowering the Value of This Tunable?
The system may run out of
What Other Tunables Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of
HP-UX.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun-
able values, consult the documentation for the kernel software being installed. For information about optional kernel software that was
factory installed on your system, see at
AUTHOR
was developed by HP.
SEE ALSO
kctune(1M), privileges(5), termio(7).
Tunable Kernel Parameters nclist(5)