Subfield a: CD
Subfield b: ES, TCHA, EO, M-39

A1:It is ANSCR (although the "CD" prefix is technically not part of the ANSCR scheme). The correct tag is 098 with indicators 14. The entire call number should go into subfield a. There is no 098 subfield b.

A2:It is an ANSCR number. ES means symphonies, TCHA is the composer. EO is a combination of the first letters of two significant words in the title. The last section would be for the surname of the orchestra conductor. If there are many, and none is featured, the ANSCR book recommends using the first initial of the record company's name and the last two digits of the associated number, which is what you seem to have here. (For what it's worth, we would have put all but the last segment in subfield "a", but I don't suppose it matters.)
I have no idea about the proper MARC tag--when we used ANSCR, we put it in 092, but I seldom imported a record that already had an ANSCR call number.

A3:Thanks to those who replied on and off list to my ANSCR question. I received advice that (1) field 098 with indicators 14 is appropriate to use, and (2) this field will not be retained in the master record. So I used that field accordingly.
But I also recorded the same information in field 084, Other Classification Number, entering anscr in subfield 2, Source of Number, as found in www.loc.gov/marc/relators/relahome.html Hopefully that field will be retained in the master record. Libraries that locally require the data to be located in field 098 will then be able to cut-and-paste the data into that field. Use of field 084 does seem appropriate according to the documentation.

A4:ANSCR (The Alpha-numeric system for classification of recordings) is valid for use in field 084, such as

084   ES, TCHA, EO, M-39 $2 anscr   OR as suggested                          
084   ES, TCHA, EO $b M-39 $2 anscr