User's Guide


Virtual machine options

The [VM Options] section in the abt.ini file allows you to control certain features of the virtual machine. Many of the options available in the [VM Options] section are described in Command line arguments.

You specify options using the following format:

maximumMemoryLimit=<number of bytes>

The available options include the following:

allocationIncrement
The -miXXXX command-line option, which sets the segment increment for allocation from the operating system to be XXXX bytes in size. When the executable is out of memory, a new segment of XXXX bytes is allocated from the operating system. The default allocation size is 2048K.

codeCacheSize
The -mcXXXX command-line option, which sets the size (in bytes) of the dynamic translation code cache on OS/2 and Windows. Use -mcd to disable dynamic translation for the session. Any size less than 262144 will also disable dynamic translation. The default code cache size is 2000000. This option applies only to the current session; the -mc value is not saved in the image.

copyOnWrap
For Windows systems, this option controls the call-out behavior. Specify either of the following values:
0
No copy on segment wrap
1
Copy on segment wrap

fixedSpaceSize
The -mfXXXX command-line option, which sets the size of fixed space to be XXXX bytes in size. The default is the size of the fixed space in the image when it was saved. In a newly packaged image, the default size is the actual byte size required by the image, plus a small amount.

lowMinimum
The -mlXXXX command-line option, which sets the minimum size of free memory after a global garbage collection to be XXXX bytes in size. The garbage collector uses this value to determine if it needs to allocate additional memory or return memory to the operating system. You use this option to specify a minimum amout of oldspace to remain free after a global garbage collection, and thus defer a garbage collection. The default minimum size is 500K.

maximumMemoryLimit
The -mxXXXX command-line option, which sets the maximum memory allocatable by the executable for object memory. The default is unlimited. If you set this option, the executable will stop requesting more memory from the operating system when memory allocation exceeds XXXX bytes. To disable dynamic memory allocation, you can specify -mx1.

messageLevel
This option specifies that non-zero values cause verbose output.

newSpaceSize
The -mnXXXX command-line option, which sets the size of new space to be XXXX bytes in size. The default is the size of the new space in the image when it was saved. In a newly packaged image, the default size is 256K.

oldSpaceSize
The -moXXXX command-line option, which sets the size of the largest old space to be XXXX bytes in size. The default is the size of the old space in the image when it was saved. In a newly packaged image, the default size is the actual byte size required by the image.

runtimeFlags
The -rX command-line option, which is described in Minimizing memory footprint during IC loading. The runtimeFlags value is the sum of values for the desired runtime flags. The available flags include the following:
1
RUNTIME_NO_FILEPOINTERS
2
RUNTIME_NO_CMINFO
4
RUNTIME_NO_CATEGORIES
8
RUNTIME_NO_APPLICATIONS
16
RUNTIME_DUMP_IMAGE_ON_ERROR

Flags 1 through 8 apply to ICs only. Flag 16 applies to any runtime executable.


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