This variable is used to change the default behavior of a CANCEL ALL statement. The default behavior is for CANCEL ALL to free all DLLs and UNIX/Linux shared object libraries loaded with a prior CALL statement. Setting CANCEL_ALL_DLLS to "\0 (off, false, no) indicates that CANCEL ALL should not free any DLLs or shared object libraries. If you want to free a particular DLL or shared library when CANCEL_ALL_DLLS is set to 0, you must specify the DLL's name in a CANCEL statement.
The default value of CANCEL_ALL_DLLS is 1 (on, true, yes).