MFS Reversal utility overview

The MFS Reversal utility converts MFS MID, MOD, DIF, and DOF control blocks back into IMS™ MFS utility control statements. The MFS Reversal utility is helpful in cases where the MFS source files are lost or compromised.

Note: MID refers to Message Input Descriptor, MOD to Message Output Descriptor, DIF to Device Input Format, and DOF to Device Output Format.

Subsections:

Function overview
Program structure

Function overview

The MFS Reversal utility builds a list of the selected MIDs and MODs and generates a list of all DIFs and DOFs that are associated with them. It then builds the source for the selected MIDs and MODs and linked DIF and DOF MFS control blocks and saves them as members of a partitioned data set.

If the input to MFS Reversal contains a single name ALL, then the utility builds the source for all MID, MOD, DIF, and DOF MFS control blocks of the IMS MFS format library.

It also generates a summary report of the relationships between MIDs/MODs and DIFs/DOFs, and relationships between MIDs and MODs of the specified MFS format library.

The MFS Reversal utility also provides a function to copy the selected MFS control blocks (MIDs, MODs, DIFs, DOFs) and their associated control blocks from the IMS format library to a user-specified partitioned data set. The utility also generates a report that summarizes the results of the copy process. You can use this function to back up the MFS control blocks.

Program structure

The MFS Reversal program consists of two load modules. One of them, called FABVRVRS, is the actual utility program. The second is a Device Characteristics Table called DFSUDT0x. The suffix x has a default value of A, but you can select another suffix using a control statement of the MFS Reversal utility. This module is fetched from your IMS RESLIB. A default Device Characteristics Table called FABVDVCT is provided with MFS Reversal in case you do not have the DFSUDT0x module. The DFSUDT0x table describes the default characteristics of 3270-An devices.