You can change the value of a logical variable using the EVAL debug command.
CL declarations: DCL VAR(&LGL1) TYPE(*LGL) VALUE('1') DCL VAR(&LGL2) TYPE(*LGL) Debug command: EVAL &LGL1 Result: &LGL1 = '1' Debug command: EVAL &LGL1 = X'F0' Result: &LGL1 = X'F0' = '0' Debug command: EVAL &LGL2 = &LGL1 Result: &LGL2 = &LGL1 = '0'