how to determine if a table has a primary key

 I need the primary keys of the below tables

CS_INCIDENTS_ALL_B, CS_INCIDENTS_TYPES_B,

CS_INCIDENT_STATUSES_B,

JTF_TASKS_B, JTF_TASK_STATUSES_B, JTF_TASK_TYPES_B ,

JTF_TASKS_AUDIT_B,

JTF_TASK_TEMP_GROUPS_B, JTF_TASK_TEMP_GROUPS_TL,

JTF_TASK_TEMPLATES_B, JTF_TASK_TEMPLATES_TL,

CUG_SR_TYPE_ATTR_MAPS_VL

I am using the following SQL,with out success.Can any one advice?

 

SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner

FROM all_constraints cons, all_cons_columns cols

WHERE cols.table_name = 'CS_INCIDENTS_ALL_TL'