Using the ASAM services through GSAM replacement

This section describes the ASAM services that are available through GSAM replacement and summarizes the requirements for implementing ASAM services through GSAM replacement. GSAM replacement is provided with AR/CTL for IMS. It is for use in IMS and IMS compatible application programs.


If an IMS program uses a program option member that contains any data set option members specifying sequential interception, local VSAM access, or remote VSAM access, AR/CTL forces the use of GSAM replacement.

To use GSAM replacement, the application program issues IMS format GSAM calls. These calls are identical to IMS GSAM calls; if the program already uses GSAM calls, no change is necessary.

The following table summarizes information about the IMS format calls that an IMS or IMS compatible application program can issue to request ASAM support.

GSAM replacement ASAM call summary

Function code




Explicitly close an ASAM data set.

CLSE call


Retrieve the next sequential record from an ASAM data set.

GN call


Retrieve a unique record from an ASAM data set, as identified by the RSA.

GU call


Insert a segment in an ASAM data set.

ISRT call


Explicitly open an ASAM data set.

OPEN call

This section contains the following topics:

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