3.1.1 Environment Variables

The following environment variables can be set before starting SICStus Prolog. Some of these override the default sizes of certain areas. The sizes are given in bytes, but may be followed by `K' or `M' meaning kilobytes or megabytes respectively.

SP_CSETLEN
Selects the sub-code-set lengths when the EUC character set is used. For the details, see WCX Environment Variables.
SP_CTYPE
Selects the appropriate character set standard: The supported values are euc (for EUC), utf8 (for Unicode) and iso_8859_1 (for ISO 8859/1). The latter is the default. For the details, see WCX Environment Variables.
SP_PATH
This environment variable can be used to specify the location of the Runtime Library (corresponding to the third argument to SP_initialize()). In most cases there is no need to use it, but see CPL Notes.
TMPDIR
If set, indicates the pathname where temporary files should be created. Defaults to /usr/tmp.
GLOBALSTKSIZE
Governs the initial size of the global stack.
LOCALSTKSIZE
Governs the initial size of the local stack.
CHOICESTKSIZE
Governs the initial size of the choicepoint stack.
TRAILSTKSIZE
Governs the initial size of the trail stack.
PROLOGINITSIZE
Governs the size of Prolog's initial memory allocation.
PROLOGMAXSIZE
Defines a limit on the amount of data space that Prolog will use.
PROLOGINCSIZE
Governs the amount of space Prolog asks the operating system for in any given memory expansion.
PROLOGKEEPSIZE
Governs the size of space Prolog retains after performing some computation. By default, Prolog gets memory from the operating system as the user program executes and returns all free memory back to the operating system when the user program does not need it any more. If the programmer knows that her program, once it has grown to a certain size, is likely to need as much memory for future computations, then she can advise Prolog not to return all the free memory back to the operating system by setting this variable. Only memory that is allocated above and beyond PROLOGKEEPSIZE is returned to the OS; the rest will be kept.
SP_ULIMIT_DATA_SEGMENT_SIZE
Sets the maximum size of the data segment of the Prolog process. The value can be unlimited or a numeric value as described in the first paragraph in this section. A numeric value of zero (0) is equivalent to unlimited. Only used under UNIX.

In addition the following environment variables are set automatically on startup.

SP_APP_DIR
The absolute path to the directory that contains the executable. Also available as the application file search path.


SP_RT_DIR
The full path to the directory that contains the SICStus run-time. If the application has linked statically to the SICStus run-time then SP_RT_DIR is the same as SP_APP_DIR. Also available as the runtime file search path.


SP_LIBRARY_DIR
The absolute path to the directory that contains the SICStus library files. Also available as the initial value of the library file search path.

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