Specifies the number of cache buffers for a BG database. This qualifier requires standalone access.The format of the GLOBAL_BUFFERS qualifier is:

-G[LOBAL_BUFFERS]=integer

For more information on ways to determine good working sizes for GLOBAL_BUFFERS, refer to Chapter 4: “Global Directory Editor”.

In general, increasing the number of global buffers improves performance by smoothing the peaks of I/O load on the system. However, increasing the number of global buffers also increases the memory requirements of the system, and a larger number of global buffers can increase the probability of the buffers getting swapped out. If global buffers are swapped out, any performance gain from increasing the number of global buffers will be more than offset by the performance impact of swapping global buffers. Most applications use from 1,000 to 4,000 global buffers for database regions that are heavily used. FIS does not recommend using fewer than 256 buffers except under special circumstances.

The minimum is 64 buffers and the maximum is 65536 buffers. By default, MUPIP CREATE establishes GLOBAL_BUFFERS using information entered in the Global Directory.

On many UNIX systems, default kernel parameters may be inadequate for GT.M global buffers, and may need to be adjusted by a system administrator.