abap/table_sharing is a SAP Parameter attribute which is used to control Enables sharing of internal tables 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 .
Enables the sharing of internal tables. Two tables assigned to each
other refer to the same data if this option is enabled.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.