Adjusting for Daylight Saving Time DST

(PTF  BPC6421 applied)

To adjust MainView for CICS  for any time changes related to Daylight Saving Time (DST), we recommend that you perform the following tasks: 

• Ensure that CICS targets are running with AUTORESETTIME=IMMEDIATE specified or, issue the CEMT PERFORM RESET command after the time change so that the CMRDETL records will have the correct time in the key of the record.   
• Stop the  MainView for CICS  BBI-SS PAS
• Perform the DST time change
• Enter the CEMT PERFORM RESET command (if necessary)
• Re-start the BBI-SS PAS

Problems that can occur if you do not restart the BBI-SS PAS  

MainView for CICS  maintains time-related data in various control blocks in the BBI-SS PAS and the CICS regions that are executing  MainView for CICS . This data is used to calculate many fields that are used by  MainView for CICS  monitors and task performance data.  If you do not restart the BBI-SS PAS after the DST time change, the data might not contain the correct information. This situation could result in misleadingly large values after the "spring forward" time change or negative values after the "fall back" change. The following sections describe the problems that might occur.

Problems with FIC2 transaction

• During the fall back time change, the FIC2 transaction (which runs every minute in CICS to collect CMR and CICS statistics) might be set to run in the next hour instead of the next minute. The next scheduled transaction would then continue to run every minute.
  
  
• The spring forward time change might cause the next FIC2 transaction to run immediately, possibly producing one (or more) of the following messages to display in the CICS job log:
  
  FT003W PREVIOUS EXECUTION OF FIC2 IS STILL ACTIVE 

Problem with online access to CMRDETL data via CHIST or CHISTORY 

• For data space recording, you might have problems (such as no data found, missing data, or duplicate data) in the CMRDETL data as long that the data space contains data from before the DST change and after the time change. To resolve this problem, enter the commands QOFF and QON via the FST2 command or on the CREGAGT view. 
  
  
• VSAM recording uses a small data space buffer to hold CMRDETL records that might not yet have been written to the data set. The data is first read from the buffer and then  MainView for CICS  reads the VSAM data from the last record in the data space. This buffer might cause a problem (such as no data found, missing data, or duplicate data) while viewing CMRDETL records if the buffer contains data from before the DST time change and after the time change. 
  
  This will happen only during the fall back time change and the problem resolves itself after the data space is filled with data that occurs an hour after the DST time change.  Unfortunately, this is true even if you restart the BBI-SS PAS, but the time change occurs early in the morning when CMRDETL data is not often accessed online.
  
  
• For a spring forward DST time change, to see data online you must add an hour when selecting the data that was created after the time change. 
  
  For a fall back DST time change, to see data online you must subtract an hour when selecting the data that was created before the time change.
  
  Apply the PTF from APAR BAC4675 before the DST time change to eliminate the need to adjust the hour to display the data. An alternative solution is enter QOFF and QON via the FST2 command or on the CREGAGT view.