When you do not specify the SPOOL, TEMPORARY, or PERM options, MODIFY DATABASE places an ACCESS lock on the database being altered to run concurrently with all DML requests.
Modifying the SPOOL, TEMPORARY, and PERM options require an EXCLUSIVE lock.
This statement also places a rowhash-level WRITE lock on the database for DBC.DBase. The SPOOL, TEMPORARY, and PERM options then place a second lock on the immediate parent for DBC.DBase. For PERM, the second lock is a rowhash-level WRITE lock. For SPOOL or TEMPORARY, the second lock is a rowhash READ lock.
The SPOOL, TEMPORARY, and PERM options also place a rowhash-level WRITE lock on DBC.DataBaseSpace. The PERM option then places a second rowhash-level WRITE lock on the immediate parent for DBC.DataBaseSpace.