thanks to etom and jack.
Yes, i mean "in what library (or file) can I find a copybook that's used in my program". my shop use os/390. and i find it's sometimes diffcult to find one copybook exists in which PDS.whether there is a tso command or utility which functions is find the copybook's location.
By using that command,i need not use ISPF 3.4 and manually locate whether that copybook is in current PDS. If not, i open aother PDS, again locate again. I know in unix,there is a command which name is find, which have that complete same function.
regards
Hu Jun