STREAMS-UX Programmer's Guide (February 2007)

STREAMS Kernel Tunable Parameters
NSTRPUSH
Appendix H
300
NSTRPUSH
The maximum number of STREAMS modules in a single stream.
Values
Failsafe
16
Default
16
Allowed
0 - 2147483647
Recommended
16
Description
This tunable defines the maximum number of STREAMS modules that can be pushed onto a stream. This
provides some protection against run-away processes that might automatically select modules to push onto a
stream. It is not intended as defense against malicious use of STREAMS modules by system users.
Most systems do not require more than about three or four modules in a stream. However, there may be some
unusual cases where more modules are needed. The default value for this tunable allows as many as 16
modules in a stream, which should be sufficient for even the most demanding installations and applications.
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?
When the system experiences a lot of low memory situations.
What are the Side Effects of Raising the Value of This Tunable?
If too big a number is chosen, the STREAMS subsystem preallocates more memory for internal data struc-
tures than necessary. This reduces the amount of memory available to applications and the system.