Ensuring the pre-load list for the IMS adapter is up to date can make a significant difference to the performance of an IMS Message Processing Region that makes use of IBM MQ verbs such as MQPUT.
The list of modules in the pre-load list has recently changed to include CSQBAPPL, such that the list is now:
In our tests where the IMS Message Processing Program (MPP) connected to a queue manager, put a message to a queue and then got a reply message from a separate queue, there was a 3 times increase in throughput with a cost reduction of up to 55% in the IMS Message Processing Region (MPR). The improvement in performance would depend on how much the transaction was being impacted by having to load the module for each transaction.
A second less marked performance improvement was to add the load library containing the CSQQDEFV module, which contains the list of IBM MQ queue managers that the IMS subsystem connect to, into the Virtual Lookaside Facility (VLF) using the CSVLLAxx member in SYS1.PARMLIB.
For example we set up a CSVLLAMQ member containing:
Then issuing /F LLA,UPDATE=MQ, we saw further benefits in transaction rate of up to 10%.
The Knowledge Center discusses what needs to be configured for the CSQQDEFV module and provides the latest list of IBM MQ modules to be pre-loaded in section "Defining IBM MQ to IMS".