Interpreting the information

When you look at the data produced by the GTFTRACE command, consider the following points:

 

The control blocks traced

Table 11 illustrates which control blocks are traced for different MQI calls.

Table 11. Control blocks traced for WebSphere MQ MQI calls
MQI call Entry Exit
MQOPEN MQOD MQOD
MQCLOSE None None
MQPUT MQMD, MQPMO, and the first 256 bytes of message data MQMD, MQPMO, and the first 256 bytes of message data
MQPUT1 MQMD, MQOD, MQPMO, and the first 256 bytes of message data MQMD, MQOD, MQPMO, and the first 256 bytes of message data
MQGET MQMD, MQGMO MQMD, MQGMO, and the first 256 bytes of message data
MQINQ Selectors (if SelectorCount is greater than 0) Selectors (if SelectorCount is greater than 0)

Integer attributes (if IntAttrCount is greater than 0)

Character attributes (if CharAttrLength is greater than 0)

MQSET Selectors (if SelectorCount is greater than 0)

Integer attributes (if IntAttrCount is greater than 0)

Character attributes (if CharAttrLength is greater than 0)

Selectors (if SelectorCount is greater than 0)

Integer attributes (if IntAttrCount is greater than 0)

Character attributes (if CharAttrLength is greater than 0)

Note:
In the special case of an MQGET call with the WAIT option, a double entry is seen if there is no message available at the time of the MQGET request, but a message subsequently becomes available before the expiry of any time interval specified.

This is because, although the application has issued a single MQGET call, the adapter is performing the wait on behalf of the application and when a message becomes available it reissues the call. So in the trace it will appear as a second MQGET call.

Information about specific fields of the queue request parameter list is also produced in some circumstances. The fields in this list are identified as follows:

Identifier Description
BufferL Buffer length
CompCode Completion code
CharAttL Character attributes length
DataL Data length
Hobj Object handle
IntAttC Count of integer attributes
pObjDesc Object descriptor
Options Options
pBuffer Address of buffer
pCharAtt Address of character attributes
pECB Address of ECB used in get
pGMO Address of get message options
pIntAtt Address of integer attributes
pMsgDesc Address of message descriptor
pPMO Address of put message options
pSelect Address of selectors
Reason Reason code
RSVn Reserved for IBM
SelectC Selector count
Thread Thread
UOWInfo Information about the unit of work
Userid CICS or IMS user ID, for batch or TSO this is zero