Data protection by overwriting means that the user specifically deletes files that are no longer required by overwriting them. The data is physically deleted by this operation, i.e. overwritten with X'00'. Overwriting of data is controlled locally by the LMSCONV statement DELETE-ELEMENT or globally in MODIFY-DEFAULTS, by the DESTROY-DATA operand in each case.
The DESTROY-DATA operand is on the one hand a member attribute, i.e. overwriting automatically acts on this member, and on the other hand a processing parameter of the LMSCONV statement DELETE-ELEMENT. As a processing parameter, DESTROY-DATA causes all members covered by the statement to be overwritten on deletion.
The data is overwritten with X'00' if one of the following specifications calls for overwriting:
system parameter DESTLEV
specification for member: value of DESTROY-DATA on last creation or on last write access to the member
specification via the DESTROY-DATA operand in the MODIFY-DEFAULTS statement