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BLINKER OVERLAY OPSIZE
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Purpose : Request a size for the overlay pool
Syntax : BLINKER OVERLAY OPSIZE <nusize>
Default : 40 kb
Example : # increase the overlay pool size to 60kb
BLINKER OVERLAY OPSIZE 60
This command is used to set the operating size of the overlay pool at
run time in kb. It can be set to any value between 12 and 128. The
default operating size is 40kb. This may be made smaller to save memory
or larger to reduce the number of disk accesses made by the overlay
manager to re-load overlaid procedures.
When overlays are specified in the link script file, Blinker will
determine the size of the smallest possible overlay pool by adding
approximately 8kb to the size of the largest overlay unit (a segment for
most compilers). This minimum value will be displayed along with the
value specified in the BLINKER OVERLAY OPSIZE command. If the minimum
value is greater than the value specified, the minimum value will
override the value specified.
The overlay opsize may be adjusted at runtime through the use of the
BLINKER environment variable (see the 'Environment Variable' section in
Chapter 2). For a discussion of how the overlay pool is used at
runtime, see the 'Overlay Pool' section in Chapter 3.
When using Clipper Summer '87 and the DYNAMIC overlay allocation method
(see BLINKER OVERLAY DYNAMIC), the minimum OPSIZE is not displayed as it
cannot be calculated at link time. The actual OPSIZE required while
executing the program can be determined by setting it to a small value
such as 10kb, running through all the options of the application WITHOUT
performing a BLIOVLCLR(), and then checking the value of the Blinker
function BLIOVLOPS() just before quitting the program. The value
returned by the BLIOVLOPS() function will be the minimum value for the
OPSIZE.
The reason for this is that with the DYNAMIC method all active overlays
must remain in memory at a given time. The minimum overlay OPSIZE is
therefore the total size of the active overlays when the program is at
its deepest level of nesting. The method described above may be used to
establish this value, and setting it to a smaller value will simply
cause the value to be overridden at runtime.
See Also:
ENVIRONMENT NAME
BLIOVLOPS()
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