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.