JVM default values for -Xms (minimum heap size) and -Xmx (maximum heap size) if they are not set
 Technote (troubleshooting)
 
Problem(Abstract)
This describes the Java™ virtual machine (JVM™) default values for -Xms (minimum heap size) and -Xmx (maximum heap size) if they are not set within WebSphere® Application Server. Note that if the initial and maximum heap values are set in WebSphere Application Server, it will override these default values.
 
Resolving the problem
When initial and maximum heap values are set in WebSphere Application Server, default values are overridden.
To determine if these values are set in WebSphere Application Server, use the administrative console to navigate to the appropriate tab for the JVM settings. If the "initial heap size" or "maximum heap size" fields are blank, the following default values will be used.

Default sizes for -Xmx (maximum heap size)
  • 1.2.2 and 1.3.0
    • Microsoft® Windows®: Half the real storage with a minimum of 16 M and a maximum of 2 G
    • AIX®, z/OS, Linux®, Solaris™: 64 M
  • 1.3.1
    • Windows: Half the real storage with a minimum of 16 M and a maximum of 2 G
    • AIX, and z/OS: 64 M
    • Linux: Half the real storage with a minimum of 16 M and a maximum of 512 M
    • Solaris: 64 M
    • HP-UX: 64 M
  • 1.4.1
    • Windows: Half the real storage with a minimum of 16 M and a maximum of 2 G
    • AIX, and z/OS: 64 M
    • Linux: Half the real storage with a minimum of 16 M and a maximum of 512 M
    • Solaris: 64 M
    • HP-UX: 64 M
  • 1.4.2
    • Windows: Half the real storage with a minimum of 16 M and a maximum of 2 G
    • AIX, and z/OS: 64 M
    • Linux: Half the real storage with a minimum of 16 M and a maximum of 512 M
    • Solaris: 64 M
    • HP-UX: 64 M

Default sizes for -Xms (minimum heap size)
  • 1.2.2 and 1.3.0
    • Windows: 4 M
    • AIX, z/OS, Linux, Solaris: 1 M
  • 1.3.1
    • Windows, AIX, Linux: 4 M
    • z/OS: 1 M
    • Solaris: 3584k
    • HP-UX: 2 M
  • 1.4.1
    • Windows, AIX, Linux: 4 M
    • z/OS: 1 M
    • Solaris: 1 M
    • HP-UX: 2 M
  • 1.4.2
    • Windows, AIX, Linux: 4 M
    • z/OS: 1 M
    • Solaris: 3670k
    • HP-UX: 2 M
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Application Server for z/OS Not Applicable
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Java SDK
Operating system(s): z/OS
Software version: 6.0
Software edition:
Reference #: 1132680
IBM Group: Software Group
Modified date: Feb 17, 2005