Oracle® Solaris 11.2 Tunable Parameters Reference Manual

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Updated: December 2014



Specifies the amount of kernel pageable memory available. This memory is used primarily for kernel thread stacks. Increasing this number allows either larger stacks for the same number of threads or more threads. Default system thread stack sizes are described in lwp_default_stksize.

  • SPARC: This parameter can be modified by editing the /etc/system file.

  • x64: This parameter can be only be modified as follows:

    • Boot under the kernel debugger

    • Set a breakpoint at the beginning of the system startup process

    • Set the desired value

Data Type

Unsigned long


2 GB x the smaller result of nCPUs / 128 or the amount of physical memory / 256 GB


512 MB to 64 GB (SPARC)

200 MB to 8 GB (x64)






Value is compared to minimum and maximum sizes. If smaller than the minimum or larger than the maximum, it is reset to 2 GB. A message to that effect is displayed.

On SPARC systems, the segkpsize value cannot exceed twice the size of physical memory. On x64 systems, the value cannot exceed the size of physical memory.

When to Change

Required to support large numbers of processes on a system. The default size allows creation of 32- KB stacks for 65,535 kernel threads. The size of a kernel stack in a 64-bit kernel is the same whether the process is a 32-bit process or a 64-bit process.

Commitment Level