MEM-FLUSHBLOCKS <number of blocks>
This option controls when a background thread flushes trace data into the flush file without blocking the application. It has no effect if AUTOFLUSH is disabled. Setting this option to a negative value also disables the background flushing.
Flushing is started whenever the number of blocks in memory exceeds this threshold or when a thread needs a new block, but cannot get it without flushing.
If the number of blocks also exceeds MEM-MAXBLOCKS, then the application is stopped until the background thread has flushed enough data.