Description: The amount of memory (in bytes) that this JMS server can use to store message bodies before it writes them to disk. When the JMS server writes the message bodies to disk, it clears them from memory. A value of -1 (the default) specifies that the server will automatically determine a size based on the maximum heap size of the JVM. This default will be set to either one-third the maximum heap size, or 512 megabytes, whichever is larger. The larger the buffer, the more memory JMS will consume when many messages are waiting on queues or topics. Once the buffer is surpassed, JMS may write message bodies to the directory specified by PagingDirectory in an effort to reduce memory usage below this buffer. Surpassing the buffer size does not stop the JMS server from accepting new messages. It is still possible to run out of memory if messages are arriving faster than they can be written to disk. Users with high messaging loads who wish to support the highest possible availability should consider setting a quota or setting a threshold and enabling flow control. Paging is always supported.