On swissinfo.ch, Fabio Canetg explains how the Swiss National Bank prevents banks from hoarding cash rather than holding reserves at the central bank (which pay negative interest). He points to the following sentence in the SNB’s December 2014 press release (my emphasis) and he speculates that banks could, in principle, implement similar schemes to keep depositors from withdrawing cash:

The threshold currently corresponds to 20 times the minimum reserve requirement for the reporting period 20 October 2014 to 19 November 2014 (static component), minus any increase/plus any decrease in the amount of cash held (dynamic component). The change in the amount of cash held is calculated as the difference between the average cash holdings during the most recent reporting period for which the minimum reserve requirement is determined prior to the reference date (cf. section 5 below) and the cash holdings of the corresponding reporting period in a given reference period.