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JAVA command keywords:
GCHINL
Initial heap size.
The possible value range is 256-240000000 kilobytes.
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For more information about the GCHINL keyword refer to the i5/OS JAVA (Run Java Program) command.
GCHMAX
Maximum heap size.
The possible value range is 256-240000000 kilobytes.
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The 32-bit JDK can only have a process address space of 4096M (16 segments) and some of these segments are reserved.
Segment Count | Segment MB | GCHMAX Value |
|---|---|---|
1 | 256 | 262144 |
2 | 512 | 524288 |
3 | 768 | 786432 |
4 | 1024 | 1048576 |
5 | 1280 | 1310720 |
6 | 1536 | 1572864 |
7 | 1792 | 1835008 |
8 | 2048 | 2097152 |
9 | 2304 | 2359296 |
10 | 2560 | 2621440 |
11 | 2816 | 2883584 |
12 | 3072 | 3145728 |
13 | 3328 | 3407872 |
… | ||
16 | 4096 | 4194304 |
… | ||
20 | 5120 | 5242880 |
… | ||
24 | 6144 | 6291456 |
… | ||
915 | 234240 | 239861760 |
From experimentation, these are the maximum GCHMAX values for IBM Java Technology for Java JDK's.
32bit JVM's are limited to 3407872 kilobytes: STRJSM
STRJSM VERSION(*JVM8032) GCHMAX(3407872)
64bit JVM's are limited to 239861760 kilobytes: STRJSM
STRJSM VERSION(*JVM8064) GCHMAX(239861760)
If you are using the shared classes option (-Xshareclasses), then the maximum GCHMAX value will be less.
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