NUMBUF parameter

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Number of buffers


Default value
Parameter type
Where set
Related products
Model 204 V2.1 or earlier


This parameter specifies the number of file page buffers.

After Model 204 initialization, NUMBUF indicates the number of file page buffers actually allocated.

NUMBUF is equal to the number of buffers allocated above the line; that is, below the bar (BTB). NUMBUF is equal to or less than MAXBUF, depending on the amount of virtual storage available to the job.

Note: As of version 7.7 of Model 204, whether BTB buffers are used at all depends entirely on the setting of NUMBUFG, which activates buffer storage above the bar.

  • If NUMBUFG is greater than 0, all buffer pool buffers are forced above the bar — no buffers are below the bar. The NUMBUF and MINBUF parameters are forced to 0, and the other parameters that affect BTB storage (MAXBUF, SPCORE, LDKBMWND, and NLRUQ) are ignored.
  • If NUMBUFG is set to 0, all buffers are below the bar, and the settings of the BTB-related parameters are respected and calculated as in pre-7.7 versions.

For background information, see Disk buffers and Model 204 storage.