rdisp/max_snc_hold_time is a SAP Parameter attribute which is used to control Maximum hold time while priv SNC 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 specifies the maximum time how long a work process can
block in the security layer.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.