This statement sets the size of the user-data buffer.
Definition
A lower-level DBH option of STORAGE-SIZE
Function
The SESAM/SQL DBH administers two separate buffers: one for blocks with systemaccess data (see the DBH option SYSTEM-DATA-BUFFER on "SYSTEM-DATA-BUFFER") and one for blocks with user data. The blocks are each 4 Kbytes in size. All users use both buffers together for all connected databases.
You use the DBH option USER-DATA-BUFFER to set the initial size of the buffer for user data.
The final size of the buffer for user data depends on the DBH option THREADS and the system threads depending on THREADS. The minimum value for the buffer size is 96 KB per thread. If the specified value is smaller than the minimum value, then the value is automatically increased to the minimum value as long as the specified value is within the permitted range of values (see below). Otherwise the DBH is terminated.
You can adjust the value of the option during the DBH session by means of the RECONFIGURE-DBH-SESSION administration statement (see "RECONFIGURE-DBH-SESSION").
USER-DATA-BUFFER |
= 80 / <integer 80..64000000> |
Operands
USER-DATA-BUFFER = 80 / <integer 80..64000000>
Initial size of the buffer for user data in units of 1 Kbyte. The default is 80 Kbytes.
The maximum value for USER-DATA-BUFFER is 64 000 000 Kbytes (64 Gbytes) on all current BS2000 servers.
If the system configuration so permits, the SYSTEM-DATA-BUFFER is created in a data space. Otherwise it is created in the normal class 6 memory.
Information on input/output behavior
The “I/O” form of the SESAM/SQL monitor SESMON contains information on input/output behavior. This information helps you set the optimal size of the buffer for user data (see "DBH form I/O").
The “ Performance” manual describes the cases in which it makes sense to modify the size of the buffer for user data at the next DBH startup.