The presence of an IBMSNAP DD statement causes option DEBUG to be forced and causes SNAP macros to be issued at many places in the code. Each SNAP has a unique ID=nnn assigned. Storage headings identify the CSECT issuing the SNAP and the control block or storage area being snapped.

The DCB parameters for IBMSNAP are those documented for the SNAP macro in z/OS MVS Programming: Assembler Services Reference IAR-XCT, RECFM=VBA, LRECL=125, BLKSIZE=882 or 1632.

An IBMSNAP DD statement might also be included with jobs that invoke IEBCOPY dynamically (such as SMP) to receive debug messages when debug keywords cannot be added directly to the IEBCOPY parameter list.

The presence of the IBMSNAP DD statement is the same as if any invoker of IEBCOPY coded "DEBUG" in the PARM field. Thus, an //IBMSNAP DD DUMMY statement is enough to get the debug messages on SYSPRINT. An //IBMSNAP DD SYSOUT=A statement gets both debug messages on SYSPRINT and SNAP dumps on IBMSNAP.

The first item that appears in the IBMSNAP data set is a dump of the parameters provided to IEBCOPY, including the DD name list. Use this when IEBCOPY is dynamically invoked to find the incorrect parameters being passed to IEBCOPY.

When a load or unload of a PDSE is in progress, each record read from or written to the unload data set is SNAP. A dump of the parameters provided to IEBCOPY including the DD name list. Use this when IEBCOPY is dynamically invoked to find the incorrect parameters being passed to IEBCOPY.