A SWI-Prolog string represents a byte-string on the global stack. It's lifetime is the same as for compound terms and other data living on the global stack. Strings are not only a compound representation of text that is garbage-collected, but as they can contain 0-bytes, they can be used to contain arbitrary C-data structures.

public static PlTerm PlString(
	string text,
	int len
)

Public Shared Function PlString ( 
	text As String,
	len As Integer
) As PlTerm

public:
static PlTerm PlString(
	String^ text, 
	int len
)

static member PlString : 
        text : string * 
        len : int -> PlTerm