Different system configurations and loads can lead to poor response times. Use the statistics provided by CICS® Transaction Gateway to identify possible causes of poor response times and improve them.
You can use the statistics that are generated by CICS Transaction Gateway to establish the reasons why response times might be poor. The following statistics contain advice for improving poor response times.
Investigate CICS response times using CICS monitoring facilities and resolve any constraints that you find. Consider the setting of MAXTASK and TRANCLASS CICS server parameters.
Monitor the CICS TG statistics CS_IAVRESP and CSx_IAVRESP for each CICS server. If the value of CS_IAVRESP is higher than you anticipate for the transaction, a CICS server might be constrained, or interconnected database systems might be causing delays in transaction processing.
You can establish whether your worker threads have been queuing this is the case by considering the value in WT_ITIMEOUTS. If WT_ITIMEOUTS > 0 worker threads have been queuing. Also you can establish whether all your worker threads are in use by considering the value in WT_CCURR. If WT_CCURR = WT_CALLOC all worker threads are in use.
Increase the number of worker threads by amending the value of the maxworker configuration parameter to be equal to that of the number of connection managers. You might need to increase the EXCI pipe limits, see EXCI resource shortage. Consider reducing the value of the workertimeout configuration parameter if the queuing time is unacceptably high.
If CM_CALLOC = CM_SMAX all available connection manager threads are allocated to remote clients.
Increase the maximum number of connection managers by increasing the value of the maxconnect configuration parameter. Consider the maximum number of worker threads that you have defined.
If the response time at the remote client is higher than the value reported in GD_LAVRESP or GD_IAVRESP, there might be constraints in the network between the remote client and the Gateway daemon. If so select one or both of the following actions:
If GD_IAVRESP - CS_IAVRESP = a high value there might be constraints in the network between CICS Transaction Gateway and CICS. If so select one or more of the following actions:
You can establish whether Gateway processing time is high by using the statistics GD_IAVRESP and CS_IAVRESP. If GD_IAVRESP-CS_IAVRESP > 100 milliseconds Gateway processing time is high.
You can establish whether connection managers are queuing for worker threads by using the statistics CM_IALLOCHI and WT_IALLOCHI. If (CM_IALLOCHI > WT_IALLOCHI) and WT_IALLOCHI > 0 connection managers are queuing for worker threads.
a. GC does not free at least 50% of the heap, that is
SE_CHEAPGCMIN/SE_SHEAPMAX > 50%
b. Time spent in GC is more than 10% of processing time, that is
SE_IGCTIME/1000/GD_IRUNTIME > 10%
c. Period between GC events is less than once per second, that is
GD_IRUNTIME/SE_IGCCOUNT < 1s
If any of these three
conditions are true the JVM GC is constrained. If so increase Gateway
daemon minimum and maximum JVM heap sizes and the
associated region size