Set system values

 

Before installing WebSphere MQ for iSeries™, use the DSPSYSVAL command to check that the following system values are set to the requirements of your enterprise:

• QCCSID

• QUTCOFFSET

• QSYSLIBL

• QALWOBJRST

• QSHRMEMCTL

• QFRCCVNRST

• QMLTTHDACN

We can change these values, if necessary, using the CHGSYSVAL command.

1. QCCSID

   Every message has a coded-character set identifier (CCSID) in its header. The CCSID tag identifies the code page and character set of the source. For CCSIDs that are supported on the iSeries machine, see the iSeries National Language Support book.

   A queue manager obtains its CCSID from the job that created it. If the job CCSID is not a valid value in the range 1–65534, the queue manager uses the default CCSID value (65535) instead. You can change the CCSID used by the MQ queue manager by using the CL command CHGMQM.

   The CCSID must be either single-byte character set (SBCS), or mixed, that is SBCS and DBCS. It must not be DBCS only.

2. QUTCOFFSET

   Check that the coordinated universal time offset (QUTCOFFSET) system value has been set, to indicate the relationship between the system time and Greenwich Mean Time (GMT). You do this using the CHGSYSVAL command.

   If QUTCOFFSET is not set, it takes the default value of zero. MQ then assumes that the local system time is universal time coordinated (UTC), that is, GMT, and time stamps the MQ messages accordingly.

3. QSYSLIBL

   Ensure that QSYS2 is included in the list of libraries that make up the system part of the library list. MQ uses programs in this library for data conversion and SNA LU 6.2 communication.

   Do not have QMQM as part of the system or user portion of the library list.

4. QALWOBJRST

   Ensure that the QALWOBJRST system value is set to *ALL or *ALWPGMADP before you install MQ. If it is set to *NONE, the installation will fail.

   After installation, reset QALWOBJRST to its original value to maintain system security.

5. QSHRMEMCTL

   Ensure that the QSHRMEMCTL system value is set to 1 (Allowed).

   A value of 1 is used in environments where pointers can be shared amongst programs between different jobs.

   MQ requires this setting to use the shared memory APIs shmat and shmget and to share its pointers across jobs.

   If it is not set correctly initialization of Common Services will fail with system return code "3401" (Permission denied), and commands such as CRTMQM, STRMQM, ENDMQM, TRCMQM will fail.

6. QFRCCVNRST

   Ensure that the QFRCCVNRST system value is set to zero (Restore all objects without conversion), or 1 (Objects with validation errors are converted), before you install MQ. If it is set otherwise the installation will fail.

7. QMLTTHDACN

   Optionally set this to control the generation of messages into joblogs. Set QMLTTHDACN to 2 to get messages generated in a joblog; set it to 1 to avoid the messages. For example, the message CPD000D is an informational message that is generated when a command that is not thread-safe is issued from a multi-threaded application. Setting QMLTTHDACN to 1 avoids the message.

 

Parent topic:

Preparing the system