Sounds like a PRO-106/197...
When you lock out a channel in any search mode (including Stalker), it's added to the "global search lockout" list. To "unlock" it, you must remove it from that list via the PGM GLOB menu's "SRCH L/Outs" item.
SPCL/spcl indicates whether "Special Stalker mode" is on or off. From page 60 in the PRO-106 manual: "spcl=Special Stalker off, SPCL=Special Stalker on, locks out an entire 1 MHz segment if more than 5 individual lockouts in that segment".