STREAMS-UX Programmer's Guide (February 2007)

STREAMS Kernel Tunable Parameters
STRCTLSZ
Appendix H
304
STRCTLSZ
The maximum size of streams message control (bytes).
Values
Failsafe
1024
Default
1024
Allowed
0 - 2147483647
Recommended
1024
Description
STRCTLSZ limits the maximum number of bytes of control data that can be inserted by putmsg() in the
control portion of any streams message on the system. If the tunable is set to zero, there is no limit on how
many bytes can be placed in the control segment of the message.
putmsg() returns ERANGE if the buffer being sent is larger than the current value of STRCTLSZ.
Who is Expected to Change This Tunable?
Any customer.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
The tunable should be increased if the STREAMS modules or drivers require more bytes than the current
value in the control portion of any streams message.
What are the Side Effects of Raising the Value of This Tunable?
The kernel will use more memory. During low memory situations, it may bring reduce system performance
due to frequent swapping.