A Police Community Support Officer (PCSO) can stop (and search) members of the public in certain situations. The local arrangements for this vary across different force and police authority areas.
Beyond the set of standard powers that all PCSOs hold, a Chief Officer has the discretion to delegate any one of a number of further discretionary powers.
The list of both standard and discretionary powers which PCSOs can hold are outlined here.
If you would like to find out which PCSO powers are used in your area please look at the table found here.