If you set the MS Compiler directive, the LOCKING clause in the SELECT statement is supported. 
            
            General Format 
            
            
               

               
            
            
            General Rules
            
            
               
               - For SEQUENTIAL and LINE SEQUENTIAL files only EXCLUSIVE locking is allowed. 
 
               
               - If MANUAL is specified multiple locks can be applied to the file. 
 
               
               - If AUTOMATIC is specified a single lock is applied automatically to the current record. 
 
               
               - For SEQUENTIAL and LINE SEQUENTIAL files the default LOCKING mode is EXCLUSIVE. 
 
               
               - For RELATIVE and INDEXED files the default LOCKING mode is AUTOMATIC. 
 
               
               - If the MANUAL option is specified the UNLOCK statement will release all locks.