The Java Virtual Machine (JVM) option `MaxDirectMemorySize` controls the maximum total size of memory that may be used for direct buffers in an instance of the JVM. Its default value is the maximum size of the heap. Prior to JDK 24, the amount of memory allocated for internal, temporary direct buffers such as used, for example, when reading from or writing to a `java.nio.channels.FileChannel`, was included in this total. As of JDK 24, internal use of temporary direct buffers is no longer included in the total.