rdisp/core_file_size is a SAP Parameter attribute which is used to control information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter controls the soft limit of the 'core file size', which is
documented in the manpage of ulimit of your system:
'default' does not change the core file size and the initial value,
inherited from the parent process, will be kept.
'unlimited' sets the core file size to unlimited size, it is not
possible to use the system specific numeric value of unlimited.
Positive numeric values set the the core file size to the specified
value.
The default setting of this parameter value is 'default' and will not
change the active setting of the core file size. Setting the value to
default does not change the current value, it can not be used to switch
back to a previous or initial value!
See SAP Parameter Documentation for full SAP documentation for this profile parameter.