Options - Data Space
The Data Space options tab specifies the initial amounts of memory allocated to
the GenStat server for storing data of various types. Reals are used for storing numeric data, such as variates
or tables. Integers are used for storing factors and some internal system information. Characters are used for
storing textual data, such as strings and factor labels. The data allocation for each type is specified in blocks
of 32768 values. Real data values occupy 8 bytes, integers 4 bytes, and characters 1 byte, thus the memory consumed
by 1 block varies for each type as follows:
| Real | 8 bytes per value, or | 256k bytes per block |
| Integer | 4 bytes per value, or | 128k bytes per block |
| Character | 1 bytes per value, or | 32k bytes per block |
As GenStat reads in data and analyses are computed the initial allocation may be insufficient, in which case additional
memory is requested from Windows. This continues to happen until the system resources are low or exhausted, in which
case GenStat will fail with an SP 3 or SP 4 diagnostic message.
Student Limits
If GenStat is running under a Student License, the workspace will be fixed at the initial values specified and will not be
increased even if this is insufficient. The initial allocation is for 3 blocks of reals and 1 block of the other types,
and these values cannot be increased. The effect of these constraints is to limit the size of problem that can be analysed,
as indicated by the above figures.
Changing the Initial Allocation
Under normal circumstances there should be no reason to change these values. If, however, you frequently analyse "large" data
sets it may prove more efficient to use larger values for the initial memory allocation. Note that if you needlessly
increase these values you may reduce the overall performance of your system; memory allocated to GenStat not being available
to other applications.
There is an indication of memory usage in the GenStat End of Job message, printed following a JOB,ENDJOB,
or STOP directive. This indicates the current memory usage for Real data. This information, along with that
for other data types, can also be obtained by submitting the command "DUMP [PRINT=space]". If you are
considering increasing the initial allocation you should first check how much memory you are using in typical jobs. This should
confirm that a change is actually necessary, and also indicate suitable settings.
Changing these values does not have an immediate effect; the new values will be used next time the GenStat Server is started.
The Server can be restarted immediately, using the new settings, by pressing the Restart Server button.
Notes
GenStat slowly consumes memory as data structures are formed and analyses are carried out. Deleting data structures allows the
memory to be re-used. This can be done via the Display command on the Data menu. Temporary data structures are automatically
deleted at regular intervals.
When working with large amounts of data it is possible to exhaust all available memory (RAM and paging file), in which case a
system message may appear advising you that virtual memory is running low. If this happens often you may need to increase the
size of the paging file (via the Windows Control Panel) or install additional RAM. The point at which this situation may occur
will vary according to how much RAM you have, the size of the paging files, and how much memory is in use for other applications.
Apart from these considerations, there is no actual limit to the workspace available to GenStat.
See Also