Starting JAMS

Start Options

JAMS provides two primary graphical interfaces:

JAMS Launcher: Enables loading, running, and saving models, editing parameters, and analyzing results.
JAMS Builder: Permits modifying JAMS model structure (components, spatio-temporal iteration, control flow) with launcher functionality.

A command line interface also supports loading and running JAMS models.

Access these through the starter scripts in the JAMS installation root directory:

Interface	Windows	Linux / macOS
JAMS Launcher	jams.bat	jams.sh
JAMS Builder	juice.bat	juice.sh
Command line without GUI	`jams.bat -n -m <MODEL_FILE>`	`./jams.sh -n -m <MODEL_FILE>`

Setting Available Memory

Edit and update the -Xms and -Xmx options in the starter script (or pass them directly when starting Java yourself):

java -Xms100m -Xmx500m -jar jams-starter.jar

Use “m” for MB and “g” for GB units.

From command line:

java -Xms100m -Xmx500m -jar jams-starter.jar -n -m <MODEL_FILE>

Setting Location of Platform-Dependent Libraries

Use the -Djava.library.path option:

java -Djava.library.path=bin/linux64 -jar jams-starter.jar

JAMS Command Line Arguments

Short	Long	Function
-h	–help	Print help
-c	–config <config file name>	Load configuration from file
-m	–model <model definition file name>	Load model from file
-s	–snapshot <snapshot file name>	Load model from snapshot file
-n	–nogui	Suppress all graphical output
-p	–parametervalue <list of parameter values>	Provide parameter values divided by semicolons
-j	–parameterfile <parameter file name>	Load parameters from file

JAMS Without Graphical Output

Using starter scripts:

./jams.sh -n -m data/j2k_gehlberg/j2k_gehlberg.jam

Or starting Java directly:

java -jar c:/jams/jams-starter.jar -n -m c:/jams/data/j2k_gehlberg/j2k_gehlberg.jam

Either way, -n/--nogui makes JAMS run truly headless, so no splash screen or other graphical output appears. On Windows, prefer jams.bat -n / juice.bat -n over the native jams.exe/juice.exe launchers for headless use — the .exe launchers always show their splash screen briefly, since it is fixed at build time and cannot be suppressed based on command-line arguments.

Transferring Model Parameters during JAMS Start

The -p/–parametervalue argument accepts semicolon-separated parameter values assigned via positioning. Wildcards in the model configuration file use the form “%x%”, where x is a consecutive number beginning at 0.

Example:

./jams.sh -n -m data/j2k_gehlberg/j2k_gehlberg.jam -p "0.1;7;1996-11-01 7:30 2000-10-31 7:30 6 1"

Here, “%0%” gets replaced by “0.1”, “%1%” by “7”, and “%2%” by the date/time string. This enables batch processing of simulation runs.

Alternatively, use -j/–parameterfile to load parameters from a file:

./jams.sh -n -m data/j2k_gehlberg/j2k_gehlberg.jam -j model.jmp

Parameter files contain key/value pairs (“parametername=parametervalue”), one per line, with “.jmp” file extension. These can be exported from JAMS Launcher or Builder and are found in model workspace output folders after execution.