Question & Answer
Question
I experienced a high-CPU loop in our z/OS Connect Enterprise Edition (zCEE) V2.0.7.0 server after enabling the TCP/IP Asynchronous I/O feature (ZOSAIO). I found flash item 1995692, z/OS Systems could become unresponsive and lead to IPL to recover if WebSphere Application Server Liberty z/OS Fix Pack 16.0.0.3 is installed and the new 'Asynchronous I/O' feature is being used, which described the probem as well as a workaround to specify the com.ibm.ws.tcpchannel.useZosAio=false in the bootstrap properties file for the zCEE server running Liberty at the 16.0.0.3 level.
After I added the com.ibm.ws.tcpchannel.useZosAio=false property to the zCEE server bootstrap.properties and recycled, I still see the message in our messages.log:
[1/25/17 18:51:04:327 GMT] 0000001d com.ibm.ws.tcpchannel.internal.ZosAio I CWWKO0229I: Native Asynchronous I/O support for z/OS has been activated.
Is there any other way to disable the AsyncIO feature without having to update our External Security Manager to restrict access to the BBG.AUTHMOD.BBGZSAFM.ZOSAIO resource profile?
Answer
Yes, for a z/OS Connect Enterprise Edition V2 server, you can disable the AsyncIO feature by providing each server with its own JVM_OPTIONS through the //STDENV DD statement in the started task JCL. For example, if you specify:
JVM_OPTIONS=-Dcom.ibm.ws.tcpchannel.useZosAio=false
in your //STDENV DD * statement in your zCEE server JCL and recycle the server, when you check the messages.log you will no longer see the message:
CWWKO0229I: Native Asynchronous I/O support for z/OS has been activated.
I confirmed this in my own zCEE server.
See topic Starting and stopping z/OS Connect EE in the z/OS Connect EE documentation for information on "JVM_OPTIONS=".
Also see topic Creating a z/OS Connect Enterprise Edition Server.
Bill Bulfin
IBM z/OS Connect EE Support
Product Synonym
zCEE
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Document Information
Modified date:
14 February 2023
UID
dwa1351636