Sriram,
Is the mobile extension fix pack for CICS 4.2 you are looking for part of an APAR? In particular, PM82511? And I assume the z/OS distribution you have installed is the z/OS distribution that comes with RD&T 8.5?
If that is true, in general we do not provide support for installing PTFs to an RD&T system. Our Installation and Sample Configuration Guide has the following disclaimer. "IBM does not provide support for the operating system distributions that are supplied with Rational Development and Test Environment for System z. You can apply fixes to the z/OS distribution through normal SMP/E facilities."
What that disclaimer suggests is that you can get any z/OS or product (CICS, for example) maintenance through your mainframe z/OS support channels, then apply that PTF using SMP/E to your RD&T system. You then, of course, have to ensure you get all prerequisites as well. The z/OS distribution shipped with RD&T does have SMP/E. We do not provide any documentation on how to perform SMP/E, but the SMP/E User's Guide is certainly a place to start - https://www-01.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.gim3000/toc.htm
Another option is to upgrade to RD&T 9.1, and either CICS 5.1 or 5.2 on z/OS 2.1. Both CICS 5.1 and 5.2 versions have the mobile extension fix pack already installed on our z/OS 2.1 distribution.
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