Topic
  • 3 replies
  • Latest Post - ‏2012-11-16T17:01:55Z by SystemAdmin
SystemAdmin
SystemAdmin
2736 Posts

Pinned topic How do I enable -XcompressedRefs in CICS TS 4.2

‏2012-10-26T12:14:52Z |
I am migrating a CICS Java program from TS 4.1 to TS 4.2. In the course of this I have to change from 31-Bit JRE to 64-Bit JRE.
The Java program works but performance is much worse than before. I still investigating, but the usual culprits like poor gc do not seem to apply.
Hoping to see some improvements I want to activate compressedRefs. I do not know how to enable it in CICS:

 <verbosegc xmlns="http://www.ibm.com/j9/verbosegc" version="R26_Java626_SR3_20120809_1152_B118944">
<initialized id="1" timestamp="2012-10-26T13:38:53.508">
<attribute name="gcPolicy" value="-Xgcpolicy:gencon" />
<attribute name="maxHeapSize" value="0x3c00000" />
<attribute name="initialHeapSize" value="0x3c00000" />
<attribute name="compressedRefs" value="false" />
<attribute name="pageSize" value="0x1000" />
<attribute name="requestedPageSize" value="0x1000" />
<attribute name="gcthreads" value="1" />
<attribute name="numaNodes" value="0" />
<system>
<attribute name="physicalMemory" value="4294967296" />
<attribute name="numCPUs" value="4" />
<attribute name="architecture" value="s390x" />
<attribute name="os" value="z/OS" />
<attribute name="osVersion" value="01.12.00" />
</system>

In the programs profile I tried -DIBM_JAVA_OPTIONS=-XcompressedRefs without success.

Any hints welcome
Hans-Peter
Updated on 2012-11-16T17:01:55Z at 2012-11-16T17:01:55Z by SystemAdmin
  • SystemAdmin
    SystemAdmin
    2736 Posts

    Re: How do I enable -XcompressedRefs in CICS TS 4.2

    ‏2012-10-26T19:06:05Z  
    IBM_JAVA_OPTIONS is an environment variable.

    Usage:

    export IBM_JAVA_OPTIONS="-Xcompressedrefs"
    On the other hand, -D is used to set "system properties"

    Refer:
    http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/topic/com.ibm.java.doc.user.win64amd.60/user/specifying_options.html
    http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/topic/com.ibm.java.doc.diagnostics.60/diag/appendixes/cmdline/cmdline_specifying.html
  • SystemAdmin
    SystemAdmin
    2736 Posts

    Re: How do I enable -XcompressedRefs in CICS TS 4.2

    ‏2012-10-27T10:54:12Z  
    IBM_JAVA_OPTIONS is an environment variable.

    Usage:

    export IBM_JAVA_OPTIONS="-Xcompressedrefs"
    On the other hand, -D is used to set "system properties"

    Refer:
    http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/topic/com.ibm.java.doc.user.win64amd.60/user/specifying_options.html
    http://publib.boulder.ibm.com/infocenter/javasdk/v6r0/topic/com.ibm.java.doc.diagnostics.60/diag/appendixes/cmdline/cmdline_specifying.html
    Hi Sadananda, thanks for your hint. But my question relates to the CICS-environment on z/OS. Here the JVM is launched in a non standard way and the configuration of a JVM running inside CICS is not as straightforward as when starting the JVM from a shell. Only my opinion: CICS documentation stays a little bit vague when in comes to special cases with java. Important 64-bit-related options like compressedRefs or lp are not mentioned there at all. Before I open a PMR I posted my question here, hoping someone would share his experiences with 64-bit jvm in/under CICS TS 4.2.
    A little background to the CICS story: Up to version 4.1, CICS uses the 31-bit JVM and beginning with version 4.2 I am urged to use the 64-bit JVM, even though currently we have no need for large heap sizes.
    Hans-Peter
  • SystemAdmin
    SystemAdmin
    2736 Posts

    Re: How do I enable -XcompressedRefs in CICS TS 4.2

    ‏2012-11-16T17:01:55Z  
    Simple answer to my question: I mistyped the option: While it is reported as
    attribute name="compressedRefs" value=true/false

    it has to be coded as -Xcompressedrefs (with all lower case) in the JVM's profile.