Field / Description
Tuning Formula or Default Value
(Default value is provided if there is no
tuning formula)
Maximum Heap Size (MB)
Controls the maximum size of a Java heap
allocated to each server JVM.
If this parameter is tuned correctly, it can:
v Reduce the overhead associated with the
garbage collection and the risk of
encountering an Out-Of-Memory (OOM)
condition
v Improve the server response time and
throughput
If you see a large number of garbage
collections, try increasing the value. Based
on the Operation System (OS), and whether
it is a 32-bit JVM or 64-bit JVM, and the
available memory, the maximum value that
you can go up to will change.
Based on your operating system and
architecture, the parameters are provided in
the following list:
v HP-UX 32-bit: (HP-UX.MAX_HEAP)
v HP-UX 64-bit: (HP-UX-64.MAX_HEAP)
v IBM AIX 32-bit: (AIX.MAX_HEAP)
v IBM AIX 64-bit: (AIX-64.MAX_HEAP)
v Sun Solaris 32-bit: (SunOS.MAX_HEAP)
v Sun Solaris 64-bit: (SunOS-
64.MAX_HEAP)
v Linux 32-bit: (Linux.MAX_HEAP)
v Linux 64-bit: (Linux-64.MAX_HEAP)
v Windows 32-bit: (Windows.MAX_HEAP)
v Windows 64-bit: (Windows-
64.MAX_HEAP)
v IBM iSeries OS/400: (OS400.MAX_HEAP)
v IBM OS/390: (OS390.MAX_HEAP)
tuning.properties Property:
[operating system].MAX_HEAP
Based on your operating system and
architecture, the formulae are provided in
the following list:
v HP-UX 32-bit:
If memory allocated to the server node is
greater than or equal to 3068 MB, it
allocates 3068 MB. Else, if the memory
allocated to server node is lesser than or
equal to 512 MB, it allocates 512 MB. If
the memory allocated is greater than 512
MB, but lesser than 3068 MB, it allocates
the memory allocated to each server node.
v HP-UX 64-bit:
if (MEMORY_ASI >= 3068,
MEMORY_ASI, if (MEMORY_ASI <= 512,
512, MEMORY_ASI))
v IBM AIX 32-bit:
If memory allocated to the server node is
greater than or equal to 3328 MB, it
allocates 3328 MB. Else, if the memory
allocated to server node is lesser than or
equal to 512 MB, it allocates 512 MB. If
the memory allocated is greater than 512
MB, but lesser than 3328 MB, it allocates
the memory allocated to each server node.
v IBM AIX 64-bit:
if (MEMORY_ASI >= 3328,
MEMORY_ASI, if (MEMORY_ASI <= 512,
512, MEMORY_ASI))
Performance Management 131
