Problem:

If the two files CTC321.IDX and CTC321.TRC (found in workgroup: development\\output libraries\\working output) continue to grow in size, it is an indication that all tracing and diagnostic options have been activated unnecessarily.

Resolution:

Within a CICS project click on the CICS tab > select "Active SIT" > select "Properties" > select "Diagnostics".  Within this window ensure that only the two checkboxes "Dump on Abend" and "Dump on System Abend" are activated.  All other checkboxes can be unchecked unless, of course, there is a particular problem which needs to be identified.  

Once this has been done, the two files CTC321.IDX and CTC321.TRC can be deleted.

They will be recreated the next time CICS is used.