When recording for profiling, the SIZE controls statement specifies the maximum amount of virtual storage, in megabytes, that each transaction can accumulate before it is flushed. Users can specify a value in the range 1 to 2000 inclusive. If the transaction reaches this limit then it is flushed and partially collected. Trace events that follow are ignored.
The collector retains the trace entries for each active transaction in virtual storage buffers until it ends, at which time the transaction is flushed to the archive data sets and the buffers are freed. If too many transactions are active at one time, then the collector may become short on storage and terminate. SIZE in conjunction with other filtering and collection options can prevent this from happening.
If SIZE is not specified, the default value is 20 (megabytes).