When this value is "1" (on, true, yes), the runtime system tests each use of a LINKAGE data item to make sure that the item passed by the calling program is at least as large as the item declared by the called program. This ensures that unallocated memory is not accidentally referenced. Setting this value to "0" (off, false, no) inhibits this check. The default value is "1". If you set this value to "0", you should test your programs carefully, because you may get memory corruption.