Limitations on memory allocation


I am getting below error while trying to start the IS whenever max memory is set to greater than 1.25 GB.

Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine

I am came to know that max memory has a limitation and its depended on OS And JVM used.
Could anyone please confirm the max value that can be used in this case.

Below are the additional details:

Product -> webMethods Integration Server
Version ->
Java Version -> 1.5.0_15 (49.0)
Java VM Name -> Java HotSpot™ Client VM
Java Build Info -> 1.5.0_15-b04, mixed mode
Java Vendor -> Sun Microsystems Inc.
OS -> Windows 2003
OS Platform -> x86
OS Version -> 5.2
Java Data Model -> 32-bit


Yes of course your point is valid. Other workaround is to change the OS to a 64-bit system.

Check this note from Oracle:

Why can’t I get a larger heap with the 32-bit JVM?

The maximum theoretical heap limit for the 32-bit JVM is 4G. Due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead, in practice the limit can be much lower. On most modern 32-bit Windows systems the maximum heap size will range from 1.4G to 1.6G. On 32-bit Solaris kernels the address space is limited to 2G. On 64-bit operating systems running the 32-bit VM, the max heap size can be higher, approaching 4G on many Solaris systems.

Vijay – Is there any business requirement to allocate memory of 1.25 GB ? Do we know what all integrations running in that wM IS.



it is possible in 64-bit Solaris running a 32-bit JVM to assign 3.5GB to an IS.

For technical reasons we are currently running in 64-bit mode as we have a native lib SAP connectivity which only exists as a 64-bit version.