(2) .-MAXBFRU--=--5-----------------. | (1) | +-MAXBFRU--=--1-----------------+ >>-+-------------------------------+--------------------------->< '-MAXBFRU--=--number_of_buffers-'
- MAXBFRU defaults to 1 when HPR=NO, XID=NO, CONNTYPE=LEN, or the VTAM node is not HPR capable.
- MAXBFRU defaults to 5 when HPR=YES, XID=YES, CONNTYPE=APPN, and the VTAM node is HPR capable.
| statements: | TRLE |
| range: | 1–16 |
Specifies the number of 4K buffer pages VTAM® uses to receive data when activating a multipath channel. The same MAXBFRU value is used for each of the READ subchannels. The resulting buffer size is number_of_pages multiplied by 4K. The total buffer space used is 4K multiplied by number_of_pages multiplied by the number of READ subchannels.
VTAM automatically substitutes a value of 16 for any coded value higher than 16 without issuing a warning message.
Some devices might have a hardware restriction on the maximum number of buffers. If there is a hardware buffer size for multipath channel, VTAM compares the MAXBFRU value and the hardware buffer size and uses the smaller of the two to avoid excessive fixed storage.
MAXBFRU is not used to determine the buffer size of the WRITE subchannels coded on this host. The WRITE subchannel buffer size is determined dynamically by VTAM, depending on the setting at the READ end of the channel.
You can reduce this value after examining VTAM multipath channel tuning statistics so that excessive storage is not allocated for each subchannel. To obtain tuning statistics output, code the TNSTAT start option.
For connections to an OSA-Express feature, MAXBFRU is fixed at 2 and should not be coded.