VSAM Compatibility

IAM is a high performance indexed access method, providing random and sequential access to user data with minimal computer resources. IAM provides an application program interface that is compatible to the z/OS VSAM access method, supporting the most commonly used features and capabilities. IAM can be used in place of VSAM KSDS files, which are processed sequentially or randomly by key, and VSAM ESDS files, that are accessed sequentially or randomly by relative byte address (RBA), or by control interval. IAM files can be used in place of VSAM KSDS, RRDS, or ESDS files that utilize the IAM supported functions without modification. IAM Alternate Indexes can be used for any alternate indexes related to VSAM KSDS or ESDS types of file that have been converted to IAM. IAM provides support for both fixed length record and variable length record RRDS files. While IAM does not use the VSAM LSR buffer pool, IAM can be used by applications that indicate usage of the VSAM LSR buffering, including Batch LSR and CICS. IAM files can be processed by system utility programs, including IDCAMS and any of the many SORT software products. 

Related topics

CICS-Considerations

Vendor-Products-That-Have-Converted-VSAM-Files-to-IAM

Pervasive-Encryption

IAM provides support for the VSAM exit routines, as specified in the ACB EXLST, including the SYNAD, LERAD, EODAD, JRNAD, and UPAD exit types. IAM provides support for z/OS Pervasive Encryption, allowing for use of the KEYLABEL keyword on IDCAMS Define Cluster statements or Security system Data Set Profiles.

IAM does not support accessing KSDS type of files by VSAM relative byte addressing (RBA) or by control interval processing (VSAM RPL OPTCD=ADR or OPTCD=CNV). IAM does not support control interval updates for ESDS type of files, although control interval reads and file load processing by control interval are supported. 





 

Tip: For faster searching, add an asterisk to the end of your partial query. Example: cert*