Oracle Solaris Tunable Parameters Reference Manual



Specifies the default stack size of all threads. No thread can be created with a stack size smaller than default_stksize. If default_stksize is set, it overrides lwp_default_stksize. See also lwp_default_stksize.

Data Type


  • 3 x PAGESIZE on SPARC systems

  • 2 x PAGESIZE on x86 systems

  • 5 x PAGESIZE on AMD64 systems


Minimum is the default values:

  • 3 x PAGESIZE on SPARC systems

  • 2 x PAGESIZE on x86 systems

  • 5 x PAGESIZE on AMD64 systems

Maximum is 32 times the default value.


Bytes in multiples of the value returned by the getpagesize parameter. For more information, see getpagesize(3C).


Yes. Affects threads created after the variable is changed.


Must be greater than or equal to 8192 and less than or equal to 262,144 (256 x 1024). Also must be a multiple of the system page size. If these conditions are not met, the following message is displayed:

Illegal stack size, Using N

The value of N is the default value of default_stksize.

When to Change

When the system panics because it has run out of stack space. The best solution for this problem is to determine why the system is running out of space and then make a correction.

Increasing the default stack size means that almost every kernel thread will have a larger stack, resulting in increased kernel memory consumption for no good reason. Generally, that space will be unused. The increased consumption means other resources that are competing for the same pool of memory will have the amount of space available to them reduced, possibly decreasing the system's ability to perform work. Among the side effects is a reduction in the number of threads that the kernel can create. This solution should be treated as no more than an interim workaround until the root cause is remedied.

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