Außerdem würde ich einen anderen Connection Pool empfehlen
Was ist die Alternative? Oder selber machen?

Einige Infos konnte ich noch ermitteln:

Das holen von Connections hält sich im ms Bereich, also kann man dieses ausschließen.

Was mir auffällt, dass sonst die Programme mit einer 64bit JVM laufen. Liegt es vielleicht daran?
Die AS400 hat wohl Arbeitsspeicher im 3-Stelligen Bereich
Momentan bin ich noch ratlos iund weiß nicht wo ich anfangen soll zu suchen.

Hier mal die Properties, vielleicht könnt ihr was dazu sagen?!

java.vendor = IBM Corporation
java.security.debug = false
sun.management.compiler = IBM Classic JIT
PATH = /usr/bin:.:/QOpenSys/usr/bin:/QOpenSys/bin:
os.name = OS/400
sun.boot.class.path = /QIBM/ProdData/Java400/jdk6/jdkawt.jar:/QIBM/ProdData/Java400/jdk6/lib/jdkptf16.zip:/QIBM/ProdData/Java400/jdk6/lib/ibmjssefw.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmjsseprovider2.jar:/QIBM/ProdData/Java400/jdk6/lib/IBMi5OSJSSE.jar:/QIBM/ProdData/Java400/jdk6/lib/jsse.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmjcefw.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmjaas.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmcertpathfw.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmcertpathprovider.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmpkcs.jar:/QIBM/ProdData/Java400/jdk6/lib/CmpCrmf.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmjgssfw.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmjgssprovider.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmsaslfw.jar:/QIBM/ProdData/Java400/jdk6/lib/ibmsaslprovider.jar:/QIBM/ProdData/Java400/jdk6/lib/charsets.jar:/QIBM/ProdData/Java400/jdk6/lib/resources.jar:/QIBM/ProdData/Java400/jdk6/lib/rt.jar:/QIBM/ProdData/OS/Java/jdk/lib/IBMmisc.jar:/QIBM/ProdData/Java400/
os400.defineClass.optLevel = 0
java.vm.specification.vendor = Sun Microsystems Inc.
os400.class.path.security.check = 20
os400.define.class.cache.file = /QIBM/ProdData/Java400/QDefineClassCache.jar
java.runtime.version = 1.6.0_11-b03
javax.activation.debug = false
java.compiler = jitc
os400.debug = 0
user.language = de
sun.boot.library.path = /QIBM/Proddata/Java400/jdk6/PASE32/lib/headless/:/QIBM/Proddata/Java400/jdk6/PASE32/lib/:/QSYS.LIB/QSYS2.LIB:/QSYS.LIB/QJAVA.LIB:/QSYS.LIB:/QSYS.LIB/QHLPSYS.LIB:/QSYS.LIB/QUSRSYS.LIB
java.use.policy = true
mail.debug = false
java.version = 1.6.0
os400.class.path.tools = 0
user.timezone = Europe/Zurich
java.net.preferIPv4Stack = false
sun.cpu.isalist = PowerPC
file.encoding.pkg = sun.io
file.separator = /
java.specification.name = Java Platform API Specification
os400.create.type = interpret
java.class.version = 50.0
user.country = DE
os400.verify.checks.disable = 65535
java.home = /QIBM/ProdData/Java400/jdk6
java.vm.info = build JDK-1.6, native threads, jitc
os.version = V6R1M0
os400.gc.heap.size.max = 2097152
path.separator = :
java.vm.version = 1.6
-Djava.version = 1.6
java.util.prefs.PreferencesFactory = java.util.prefs.FileSystemPreferencesFactory
sun.io.unicode.encoding = UnicodeBig
os400.vm.inputargs = -Djava.version=1.6 -Djava.awt.headless=true -Xmx2048M -Xms0512M
awt.toolkit = sun.awt.motif.MToolkit
java.specification.vendor = Sun Microsystems Inc.
java.library.path = /QSYS.LIB/QSHELL.LIB:/QSYS.LIB/QGPL.LIB:/QSYS.LIB/QTEMP.LIB::
java.vendor.url = IBM - United States
java.vm.vendor = IBM Corporation
java.runtime.name = Java(TM) 2 Runtime Environment, Standard Edition
os400.run.mode = jitc
java.class.path = ./lib/ext/start.jar:
os400.optimization = 0
java.vm.specification.name = Java Virtual Machine Specification
java.vm.specification.version = 1.0
sun.cpu.endian = big
java.awt.headless = true
java.net.preferIPv6Addresses = false
java.io.tmpdir = /tmp/
os400.job.file.encoding = Cp273
java.vendor.url.bug = IBM - United States
os.arch = PowerPC
java.awt.graphicsenv = sun.awt.X11GraphicsEnvironment
java.ext.dirs = /QIBM/ProdData/Java400/jdk6/lib/ext:/QIBM/UserData/Java400/ext
line.separator =
java.vm.name = Classic VM
java.policy = /QIBM/ProdData/Java400/jdk6/lib/security/java.policy
user.region = DE
file.encoding = ISO8859_1
os400.gc.heap.size.init = 524288
os400.stdin.allowed = 1
java.specification.version = 1.6
os400.jdk.provider = sun