Java 2 SDK for Solaris Developer's Guide

Additional Java HotSpot VM arguments

Numbers can include 'k' or 'K' for kilobytes, 'm' or 'M' for megabytes, 'g' or 'G' for gigabytes, and 't' or 'T' for terabytes (for example, 32k is the same as 32768). Turn on a boolean flag with -XX:+<option> and off with -XX:-<option>.

Flag and Default 



Do not complain if the application installs signal handlers 


Alternate signal stack size (in Kbytes) 


Bump the number of file descriptors to max 


Maximum percentage of heap free after GC to avoid shrinking 


Minimum percentage of heap free after GC to avoid expansion 


Reserved code cache size (in bytes) — maximum code cache size 


Bind user level threads to LWPs (default on in 1.4) 


Use LWP-based instead of thread based synchronization (default on in 1.4) 


Use native thread priorities 


Size of the permanent genration. 


Time spent in JIT Compiler (1.4 only) 


Print tenuring age information 


Desired percentage of survivor space used after scavenge 


Disable calls to System.gc(). VM still performs garbage collection when necessary.


On Solaris 9, this option is not necessary. On Solaris 8, J2SETM versions 1.3.1_02+ and 1.4+ require this option when using the alternate threads library. This option is not possible on pre-Solaris 8 operating environments.

For more information on threads libraries, see the threads document at

Those flags differing per architecture/OS. "Flag and Default" has the default of Sparc/-server.

Flag and Default 



Number of method invocations/branches before compiling [10,000 —server, 1,000 — client on Sparc, 1,500 on client x86] 


Maximum size of new generation (in bytes) [32m Sparc, 2.5m x86 for 1.3, no limit for 1.4 as NewRatio is now used to determine MaxNewSize]] 


Ratio of new/old generation sizes [Sparc -server: 2; Sparc -client: 4 (1.3), 8 (1.3.1+); x86: 12] 


Default size of new generation (in bytes) [Sparc 2.125M, x86: 640k] 


Ratio of eden/survivor space size [Solaris: 64] 


Thread Stack Size (in Kbytes) (0 means use default stack size [Solaris Sparc 32–bit: 512, Solaris Sparc 64–bit: 1024, Solaris x86: 256]) 

-XX:+UseTLAB (XX:+UseTLE in J2SE 1.3)

Use thread-local object allocation [Sparc -server: true, all others: false] 


See Intimate Shared Memory, online at