For example, if a transaction is updating multiple records in a dataset, it can do so in ascending key order. A transaction that is accessing more than one file should do so in the same predefined sequence of files. Do not design funnels in your applications. An example of a funnel would be making all transactions read or update the same record for information or totals. Hold resources only as long as required, rather than waiting until the task is terminated to let CICS release them for you.
Resource contention is always a big performance problem.
Transactions which do not release resources can hold up the processing of other transactions. The transactions which are held up are also holding resources which may be needed by other transactions. Eventually the whole system can grind to a halt. The trend continues to move toward more use of virtual LU names and away from SNA devices. Please notify the CICS systems group of obsolete programs, transaction ids, mapsets, files, and queues so that their definitions may be removed from the CICS tables.