java

Options for selecting the HotSpot^TM VM type

-client

The HotSpot^TM client VM is used. This VM optimizes the generated object code for short-running programs (default).

-server

The option is not supported.

-d32
-d64

The options are not supported.

Options for selecting the HSI variant

-s390

The S390 variant of JENV is used (if available). This option is useful only if both the S390 variant and the X86 variant of JENV are installed on one system and you want to explicitly select one of them for execution. This option overrides any specification in the environment variable JENV_SYSHSI (see the chapter "Environment variables"). The variant that matches your system is used by default, i.e. if no value has been assigned to the environment variable JENV_SYSHSI either.

-x86

The X86 variant of JENV is used (if available). This option is useful only if both the S390 variant and the X86 variant of JENV are installed on one SQ system and you want to explicitly select one of them for execution. This option overrides any specification in the environment variable JENV_SYSHSI (see the chapter "Environment variables"). The variant that matches your system is used by default, i.e. if no value has been assigned to the environment variable JENV_SYSHSI either.

Non-standard options

-Xmaxjitcodesize size

In contrast to the original description, the cache size is specified without an equals sign, e.g.:

-Xmaxjitcodesize48m

Controlling the Java heap memory

The following options allow the user to control heap expansion or reduction. Since the standard settings for heap expansion are suitable for most applications, it is not necessary to use these options in most situations. You should only use them if you understand the effects of the options on the applications concerned. Deliberately setting these options can just as easily adversely affect system performance as improve it.

In BS2000 the maximum size of heap memory is always requested by the system right from the start and always remains reserved in this size. Option -Xms merely controls how much of the heap memory is to be used currently. The smaller this area is, the faster garbage collection proceeds since only the area currently being used must be searched. On the other hand it can be that garbage collection has to be called unnecessarily frequently if there is only a small amount of space for new objects in the currently used area.

Minimum and default values which differ from the original description are defined for these options:

-Xsssize

Minimum value: 512K
Default value: 1M

-Xmssize

Minimum value: 1M
Default value: 3.5M

-Xmxsize

Minimum value: 1M
Default value: 64M

The specified value is rounded off the next multiple of 2M.