Each isCOBOL product, from Compiler to Application Server, is identified by a java class.

The standard way to launch these classes would be by adding the library in which they're stored to the Classpath and by issuing the command:

However, since this kind of approach would generate long commands and would require some efforts in the Classpath configuration, wrappers are provided along with isCOBOL.

These wrappers are identified by exe files on the Windows platform and by shell script files on other platforms.

They're stored in the isCOBOL bin directory.

When you launch a wrapper, the current directory ("."), all the jar libraries stored in the isCOBOL lib directory and all the jar libraries stored in the isCOBOL jars directory are automatically added to the Classpath, then your command is translated as follows:

becomes

The following table lists all the standard wrappers, which are available for all platforms, followed by the corresponding isCOBOL class

Based on the above tables, you see that, for example, using the command:

is the same as using:

All wrappers force the operating system look and feel for the application by default when running on Windows. Instead, when running on other systems, they force the Java look and feel (Metal) by default.

Launching:

is the same as launching:

On Windows platform five additional wrappers are available.

Note - isrun and isclient are the same as iscrun and iscclient except that they launch the isCOBOL class with javaw.exe instead of java.exe. In this way the java process does not keep the console busy.

For example, launching:

is the same as launching:

With these wrappers that don't display output on the console, if an unexpected exception occurs or if the program displays data upon sysout and syserr, two files named wrapper_out.log and wrapper_err.log (where wrapper can be isrun or isclient depending on the exe you launched) are updated in the isCOBOL bin directory.

Wrappers that take a program class name as parameter (e.g. iscrun, isrun, iscclient and isclient) take care of normalizing the name passed on the command line to be suitable for the Java runtime. They convert the name in upper-case, replace hyphens by underscore and strip the file extension.

For example, launching:

is the same as launching:

The -J option allows you to pass options to the JVM instantiated by the wrapper. Each option specified by -J is placed between “java” and the class name in the command generated by the wrapper. Refer to https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html for the list of available options. The most popular Java options used on the command line are -Dproperty=value to specify either a Java system property or an isCOBOL configuration property and -Xmxn to increase the maximum amount of memory that the JVM can allocate.

becomes:

becomes

becomes:

When you run the Debugger you must pay attention in using the -J option because there are two different virtual machines involved:

Options passed through -J are passed to both virtual machines, while options passed without -J are passed only to the second java virtual machine.

The following command, for example, shows how to pass a low memory limit (512 MB) to the Debugger and an high memory limit (3 GB) to the COBOL program:

That becomes:

The internal class com.iscobol.invoke.Isrun, if the -d option is used, behaves as follows: settings specified before the -d option are passed to the Debugger JVM and to the program JVM, instead settings specified after the -d option are passed only to the program JVM.

becomes:

An alternative way to pass Java options is by editing the wrapper’s vmoptions file, where applicable.

The following table lists all the wrappers that are configurable through a vmoptions file along with the name of the corresponding vmoptions file.

The vmoptions file is placed in the same folder as the wrapper and is automatically read without being specified on the command line.

Options passed through -J are appended to the options found in the vmoptions file.

Vmoptions files are particularly useful to pass Java options to Windows services, where there is no command line in which you can put your options.

Vmoptions files are text files that include a list of options. Every option is specified on a separate line. The # characters comments the line. The options should be specified with the same syntax that you would use on the command line. The -classpath option can be followed by either "/p" or "/a", in this way the option value is prepended or appended to the default Class Path built by the wrapper, that includes the libraries stored in the isCOBOL’s "lib" and "jars" folders.

For more information see for example Service configuration in isCOBOL Evolve: Application Server.